A pyrolysis reaction system and method of pyrolysing an organic feed

ABSTRACT

The invention provides a pyrolysis reaction system, the system comprising: a pyrolysis chamber comprising a feed inlet, a gas inlet and a product outlet, wherein the pyrolysis chamber is configured i) to receive a pyrolysable organic feed and an inert gas via the feed inlet and gas inlet respectively, ii) to pyrolyse the organic feed at a pyrolysis temperature to produce a carbonaceous pyrolysis product and a pyrolysis gas, wherein the pyrolysis gas will combine with the inert gas to form a gas mixture having a pyrolysis chamber pressure in the pyrolysis chamber, and iii) to discharge the carbonaceous pyrolysis product via the product outlet; a gas reactor configured to react the pyrolysis gas by combustion and/or carbon deposition at a gas reaction temperature and a gas reactor pressure; and a first partition defining a boundary between the pyrolysis chamber and the gas reactor, the first partition comprising a plurality of first apertures to provide fluid communication between the pyrolysis chamber and the gas reactor, wherein the pyrolysis reaction system is operable with the gas reactor pressure less than the pyrolysis chamber pressure such that the gas mixture flows from the pyrolysis chamber to the gas reactor through the first apertures, thereby providing at least a portion of the pyrolysis gas for reaction in the gas reactor.

TECHNICAL FIELD

The invention relates to a pyrolysis reaction system and a method ofpyrolysing an organic feed. The system comprises a pyrolysis chamberconfigured to pyrolyse an organic feed, a gas reactor configured toreact the pyrolysis gas thus formed by combustion and/or carbondeposition, and a partition that defines a boundary between thepyrolysis chamber and the gas reactor. The partition includes aplurality of apertures, such that in use a gas mixture comprising thepyrolysis gas and an inert gas flows from the pyrolysis chamber, throughthe apertures, to the gas reactor for reaction.

BACKGROUND OF INVENTION

Pyrolysis is a high temperature decomposition process for converting apyrolysable organic feed (i.e. any feed containing at least a portion oforganic, carbon-based material) under substantially inert conditions, inparticular where the oxygen content is sufficiently low that endothermiccracking reactions predominate over exothermic oxidation reactions. Lowtemperature pyrolysis (i.e. 300-350° C.) is called torrefaction, and isused for making charcoal from wood. The industrial pyrolysis normallyoperates at medium to high temperatures (350-750° C.) to produceproducts for energy, fuel or chemical applications. Pyrolysis of organicfeed materials, including various waste and biomass sources, producesthree product streams: a solid carbonaceous product (char), a pyrolysisoil fraction (which is liquid at ambient temperature) and a pyrolysisgas fraction (which is gaseous at ambient temperature and pressure).

Pyrolysis products such as gas, oil and char can be converted to anumber of value-added products or can be used in their original form fora number of applications. For example, biochar produced from pyrolysiscan be used for soil amendment, soil remediation, water purification,composites as well as fuel. The oil and gas fractions can be used asproduced or further upgraded to be used as fuels.

Various pyrolysis reaction systems have been reported for conductingindustrial pyrolysis reactions. Since pyrolysis is an endothermicreaction, it has previously been proposed to provide the required energyinput at least in part by sacrificial combustion of one or more of thepyrolysis product fractions. This is typically done by diverting aportion of the hot pyrolysis gas product (comprising the vaporized oiland/or gas fractions) to a combustion reactor adjacent to the pyrolysischamber, as schematically depicted in FIGS. 1 and 1A. Heat of combustionis thus transferred via conduction to the pyrolysis chamber from anexternal combustion reactor, as in a shell-and-tube heat exchangerarrangement, to provide the heat input necessary to drive pyrolysis.

However, the heat transfer in such systems may be unsatisfactory,particularly in larger scale reactor systems, resulting in poor heatdistribution and thus low rates of pyrolysis and/or poor or inconsistentquality of char products.

In other reported pyrolysis reaction systems, the pyrolysable feed isthermally reacted in a gas atmosphere comprising controlled amountsand/or distributions of oxygen, such that both endothermic pyrolysis andexothermic combustion or gasification reactions takes place in thepyrolysis chamber. While this may address temperature control issues inthe pyrolysis chamber, the resulting carbonaceous products may beunsatisfactory for many applications, such as in biochar production, asa result of the combustion reactions taking place.

There is therefore an ongoing need for new pyrolysis reaction systemsand methods of pyrolysing organic feeds, which at least partiallyaddress one or more of the above-mentioned short-comings, or provide auseful alternative.

A reference herein to a patent document or other matter which is givenas prior art is not to be taken as an admission that the document ormatter was known or that the information it contains was part of thecommon general knowledge as at the priority date of any of the claims.

SUMMARY OF INVENTION

In accordance with a first aspect the invention provides a pyrolysisreaction system, the system comprising:

a pyrolysis chamber comprising a feed inlet, a gas inlet and a productoutlet, wherein the pyrolysis chamber is configured i) to receive apyrolysable organic feed and an inert gas via the feed inlet and gasinlet respectively, ii) to pyrolyse the organic feed at a pyrolysistemperature to produce a carbonaceous pyrolysis product and a pyrolysisgas, wherein the pyrolysis gas will combine with the inert gas to form agas mixture having a pyrolysis chamber pressure in the pyrolysischamber, and iii) to discharge the carbonaceous pyrolysis product viathe product outlet;

a gas reactor configured to react the pyrolysis gas by combustion and/orcarbon deposition at a gas reaction temperature and a gas reactorpressure; and

a first partition defining a boundary between the pyrolysis chamber andthe gas reactor, the first partition comprising a plurality of firstapertures to provide fluid communication between the pyrolysis chamberand the gas reactor,

wherein the pyrolysis reaction system is operable with the gas reactorpressure less than the pyrolysis chamber pressure such that the gasmixture flows from the pyrolysis chamber to the gas reactor through thefirst apertures, thereby providing at least a portion of the pyrolysisgas for reaction in the gas reactor

In some embodiments, the gas reactor pressure is less than the pyrolysischamber pressure by at least 0.05 bar, such as by at least 0.1 bar, orat least 1 bar.

In some embodiments, the partition is configured such that in operationthe gas mixture flows through the first apertures at a flow ratesufficient to substantially preclude ingress of gas from the gas reactorinto the pyrolysis chamber.

In some embodiments, the first apertures comprise at least 50%, such asfrom about 80% to about 90%, of a boundary area of the first partitionbetween the gas reactor and the pyrolysis chamber. In some embodiments,the first partition comprises a mesh or perforated screen, in which thefirst apertures are formed.

In some embodiments, the partition is configured such that heat convectsfrom the gas reactor to the pyrolysis chamber through the firstapertures when the gas reaction temperature is greater than thepyrolysis temperature in operation, thereby providing at least a portionof the heat of pyrolysis in the pyrolysis chamber.

In some embodiments, the first partition comprises a thermallyconductive material, preferably a metal, such that heat conducts fromthe gas reactor to the pyrolysis chamber through the thermallyconductive material when the gas reaction temperature is greater thanthe pyrolysis temperature in operation, thereby providing anotherportion of the heat of pyrolysis in the pyrolysis chamber.

In some embodiments, the partition comprises a plurality of protrudingmembers, such as tubes or fins, that extend into the gas reactor and/orthe pyrolysis chamber, wherein at least a fraction of the firstapertures are located on the protruding members. In some embodiments,the partition comprises a plurality of spaced apart sheet members, suchas plates or meshes, that extend at least partially in a transverseorientation between the gas reactor and the pyrolysis chamber, whereinat least a fraction of the first apertures are located between thespaced apart sheet members. Such arrangements are believed to provideincreased heat transfer area for transferring heat by conduction fromthe gas reactor to the pyrolysis chamber, when the gas reactiontemperature is greater than the pyrolysis temperature in operation.

In some embodiments, the gas reactor comprises a port for introducing agas containing oxygen, preferably air, and a duct for removing flue gas,wherein the gas reactor is configured such that in operation thepyrolysis gas will react by combustion with the oxygen. Such combustionmay provide the heat transferred to the pyrolysis chamber by convectionand/or conduction.

In some such embodiments, the gas reactor comprises an annulussurrounding the pyrolysis chamber and the port is configured tointroduce the gas containing oxygen tangentially into the gas reactorsuch that a vortex flow around the pyrolysis chamber is produced in atleast a part of the annulus.

In some embodiments, the pyrolysis reaction system further comprises aflow regulator for regulating the flow rate of the gas containing oxygeninto the gas reactor in response to one or more temperature measurementsin the pyrolysis chamber. Thus, the pyrolysis reaction temperature maybe controlled within a predetermined target range by regulating theextent of combustion occurring in the gas reactor.

In some embodiments, the pyrolysis reaction system further comprises asecondary combustion reactor coupled to the duct of the gas reactor, thesecondary combustion reactor configured such that in operation unreactedpyrolysis gas present in the flue gas will react by combustion withoxygen co-fed into the secondary combustion reactor.

In some such embodiments, the pyrolysis reaction system furthercomprises a heat exchanger at least partially disposed inside the gasreactor, wherein in operation a working fluid, preferably water, isvaporised in the heat exchanger for power generation. Excess heat ofcombustion, beyond that required to provide the heat of pyrolysis in thepyrolysis chamber, may thus be converted to electrical power.

In some embodiments, the gas reactor is configured such that inoperation the pyrolysis gas will react by carbon deposition on acatalyst in the gas reactor, thereby forming a carbonaceous depositionproduct. The gas reactor may further comprise a catalyst feed inlet forfeeding a particulate catalyst and a product discharge port fordischarging a carbonaceous deposition product.

In some such embodiments, the pyrolysis reaction system furthercomprises: a combustion reactor comprising a port for introducing a gascontaining oxygen, preferably air, and a duct for removing flue gas,wherein the combustion reactor is configured to combust a fuel with theoxygen at a combustion temperature; and a second partition defining aboundary between the combustion reactor and at least the gas reactor,wherein the second partition is configured such that heat of combustiontransfers from the combustion reactor to the gas reactor through thesecond partition when the combustion temperature is greater than the gasreaction temperature in operation, thereby providing at least a portionof the heat of carbon deposition in the gas reactor. The combustion maythus produce a sufficiently high temperature in the gas reactor toprovide heat transfer from the gas reactor to the pyrolysis chamber byconvection and/or conduction.

In some such embodiments, the second partition comprises a plurality ofsecond apertures to provide fluid communication between the combustionreactor and the gas reactor, wherein in operation: i) a portion of thepyrolysis gas flows from the gas reactor to the combustion reactorthrough the second apertures, wherein the fuel combusted in thecombustion chamber comprises the portion of the pyrolysis gas; and ii)the heat of combustion transferred through the second partition at leastpartially convects through the second apertures.

In some such embodiments, the second apertures comprise at least 50%,such as from about 80% to about 90%, of a boundary area of the secondpartition between the gas reactor and the combustion reactor.

In some such embodiments, the pyrolysis chamber is configured todischarge the carbonaceous pyrolysis product into the combustionreactor, wherein the fuel combusted in the combustion chamber inoperation comprises the carbonaceous pyrolysis product.

In some such embodiments, the duct passes through the gas reactor toheat the catalyst with the flue gas.

In some such embodiments, the second partition further defines aboundary between the combustion reactor and the pyrolysis chamber,wherein heat of combustion transfers from the combustion reactor throughthe second partition to the pyrolysis chamber in operation.

In some embodiments, the first partition forms a peripheral boundary,preferably a cylindrical boundary, around the pyrolysis chamber and thegas reactor surrounds the peripheral boundary. In some embodiments, thefirst partition is rotatable relative to the gas reactor.

In some embodiments, the pyrolysis chamber is configured to fluidisesolids comprising the organic feed and/or the carbonaceous pyrolysisproduct with the inert gas. In some embodiments, a flue gas produced bycombustion of the pyrolysis gas in the pyrolysis reaction system isdirected to form at least a portion of the inert gas.

In accordance with a second aspect, the invention provides a method ofpyrolysing an organic feed, the method comprising:

feeding a pyrolysable organic feed and an inert gas to a pyrolysischamber;

pyrolysing the organic feed at a pyrolysis temperature to produce acarbonaceous pyrolysis product and a pyrolysis gas, wherein thepyrolysis gas combines with the inert gas in the pyrolysis chamber toform a gas mixture having a pyrolysis chamber pressure;

discharging the carbonaceous pyrolysis product from the pyrolysischamber;

flowing the gas mixture to a gas reactor through a plurality of firstapertures in a first partition, wherein the first partition defines aboundary between the pyrolysis chamber and the gas reactor; and

reacting the pyrolysis gas in the gas reactor by combustion and/orcarbon deposition at a gas reaction temperature and a gas reactorpressure, wherein the gas reactor pressure is less than the pyrolysischamber pressure.

In some embodiments, the gas reactor pressure is less than the pyrolysischamber pressure by at least 0.05 bar, such as by at least 0.1 bar, orat least 1 bar.

In some embodiments, the pyrolysis temperature is between about 250° C.and about 750° C., such as between 400° C. and 750° C.

In some embodiments, the gas mixture flows through the first aperturesat a flow rate sufficient to substantially preclude ingress of a gasfrom the gas reactor into the pyrolysis chamber.

In some embodiments, the gas reaction temperature is greater than thepyrolysis temperature, wherein heat convects from the gas reactor to thepyrolysis chamber through the first apertures, thereby providing atleast a portion of the heat of pyrolysis in the pyrolysis chamber. Insome such embodiments, the gas reaction temperature is greater than thepyrolysis temperature by at least about 100° C.

In some embodiments, the method further comprises introducing a gascontaining oxygen, such as air, into the gas reactor and reacting thepyrolysis gas by combustion with the oxygen.

In some such embodiments, the method further comprises regulating theflow rate of the gas containing oxygen into the gas reactor in responseto one or more temperatures measured in the pyrolysis chamber, therebymaintaining the temperatures within predetermined target ranges.

In some such embodiments, the method further comprises removing flue gasfrom the gas reactor and combusting unreacted pyrolysis gas present inthe flue gas in a secondary combustion reactor with oxygen co-fed intothe secondary combustion reactor.

In some embodiments, the method further comprises reacting the pyrolysisgas by carbon deposition on a catalyst in the gas reactor, therebyforming a carbonaceous deposition product.

In some such embodiments, the gas reaction temperature for carbondeposition is between about 600° C. and about 800° C. In some suchembodiments, the method further comprises feeding a particulate catalystto the gas reactor, and discharging the carbonaceous deposition productfrom the gas reactor.

In some such embodiments, the method further comprises combusting a fuelwith oxygen in a combustion reactor at a combustion temperature greaterthan the gas reaction temperature, wherein heat of combustion transfersfrom the combustion reactor to the gas reactor through a secondpartition that defines a boundary between the combustion reactor and atleast the gas reactor, thereby providing at least a portion of the heatof carbon deposition in the gas reactor.

In some such embodiments, the second partition comprises a plurality ofsecond apertures providing fluid communication between the combustionreactor and the gas reactor, wherein: i) a portion of the pyrolysis gasflows from the gas reactor to the combustion reactor through the secondapertures, wherein the fuel combusted in the combustion chambercomprises the portion of the pyrolysis gas; and ii) the heat ofcombustion transferred through the second partition at least partiallyconvects through the second apertures.

In some such embodiments, gas flows through the second apertures at aflow rate sufficient to substantially preclude ingress of oxygen fromthe combustion reactor into the gas reactor.

In some such embodiments, the carbonaceous pyrolysis product isdischarged into the combustion reactor, wherein the fuel combusted inthe combustion chamber comprises the carbonaceous pyrolysis product.

In some embodiments, the inert gas comprises a flue gas produced bycombustion of the pyrolysis gas. In some embodiments, the pyrolysableorganic feed comprises biomass. In some embodiments, the heat ofpyrolysis is provided by combustion of the pyrolysis gas and/or thecarbonaceous pyrolysis product without external energy input.

Where the terms “comprise”, “comprises” and “comprising” are used in thespecification (including the claims) they are to be interpreted asspecifying the stated features, integers, steps or components, but notprecluding the presence of one or more other features, integers, stepsor components, or group thereof.

As used herein, the terms “first”, and “second” in relation to variousfeatures of the disclosed devices are arbitrarily assigned and aremerely intended to differentiate between two or more such features thatthe device may incorporate in various embodiments. The terms do not ofthemselves indicate any particular orientation or sequence. Moreover, itis to be understood that the presence of a “first” feature does notimply that a “second” feature is present, the presence of a “second”feature does not imply that a “first” feature is present, etc.

Further aspects of the invention appear below in the detaileddescription of the invention.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the invention will herein be illustrated by way ofexample only with reference to the accompanying drawings in which:

FIGS. 1 and 1A schematically depict side and plan views of a pyrolysisreaction system operating according to principles disclosed in the priorart.

FIGS. 2 and 2A schematically depict side and plan views of pyrolysisreaction system 30 according to an embodiment of the invention, in whichthe gas reactor adjacent to the pyrolysis chamber is a combustionreactor.

FIG. 3 schematically depicts a side view of pyrolysis reaction system 50according to another embodiment of the invention, in which the gasreactor adjacent to the pyrolysis chamber is a carbon depositionreactor.

FIGS. 4 and 4A schematically depict front and side views of a meshpartition that defines a boundary between the pyrolysis chamber and thegas reactor in some embodiments of the invention. FIGS. 4B and 4Cschematically depict side views of parallel plate partitions that definea boundary between the pyrolysis chamber and the gas reactor in someembodiments of the invention, in which the plates are orientedhorizontally and at an inclination respectively.

FIG. 5 schematically depicts a plan view of a perforated screenpartition that defines a boundary between the pyrolysis chamber and thegas reactor in some embodiments of the invention.

FIGS. 6 and 6A schematically depict plan and side views of a partitionthat defines a boundary between the pyrolysis chamber and the gasreactor in some embodiments of the invention, wherein the partitioncomprises bubble caps in which apertures are formed.

FIGS. 7 and 7A schematically depict side views of finned partitions thatdefine a boundary between the pyrolysis chamber and the gas reactor insome embodiments of the invention, in which the protruding fin membersare oriented horizontally and at an inclination respectively.

FIG. 8 schematically depicts a side view of pyrolysis reaction system100 according to an embodiment of the invention, in which the gasreactor adjacent to the pyrolysis chamber is a combustion reactor, andin which the system produces biochar and optionally electricity asproducts.

FIG. 9 schematically depicts a side view of pyrolysis reaction system180 according to another embodiment of the invention, in which the gasreactor adjacent to the pyrolysis chamber is a combustion reactor, andin which the system produces biochar and optionally electricity asproducts.

FIGS. 10 and 10A schematically depict a side view and plan view ofpyrolysis reaction system 200 according to another embodiment of theinvention, in which the gas reactor adjacent to the pyrolysis chamber isa carbon deposition reactor and a combustion reactor is further providedadjacent to the gas reactor to provide the heat of pyrolysis and carbondeposition, and in which the system produces carbonaceous depositionproducts.

FIG. 11 schematically depicts a side view of pyrolysis reaction system300 according to another embodiment of the invention, in which the gasreactor adjacent to the pyrolysis chamber is a carbon deposition reactorand two combustion reactors are further provided to provide the heat ofpyrolysis and carbon deposition, and in which the system producescarbonaceous deposition products.

FIG. 12 schematically depicts a side view of pyrolysis reaction system400 according to another embodiment of the invention, in which the gasreactor adjacent to the pyrolysis chamber is a combustion reactor andtwo additional reactors for carbon deposition and combustion areprovided, and in which the system produces carbonaceous depositionproducts.

FIG. 13 schematically depicts a side view of pyrolysis reaction system500 according to another embodiment of the invention, in which a gasreactor adjacent to and above the pyrolysis chamber is a carbondeposition reactor, and a combustion reactor surrounding both thepyrolysis chamber and gas reactor is further provided to provide theheat of pyrolysis and carbon deposition, and in which the systemproduces carbonaceous deposition products.

FIG. 14 schematically depicts a side view of pyrolysis reaction system600 according to another embodiment of the invention, in which a gasreactor adjacent to and above the pyrolysis chamber is a carbondeposition reactor, and a combustion reactor surrounding both thepyrolysis chamber and gas reactor is further provided to provide theheat of pyrolysis and carbon deposition, and in which the systemproduces carbonaceous deposition products.

FIGS. 15 and 15A schematically depict a side view and plan view ofpyrolysis reaction system 700 according to another embodiment of theinvention, in which the gas reactor adjacent to the pyrolysis chamber isa primary combustion reactor, a remote secondary combustion reactor isfurther provided to complete the combustion, and in which the systemproduces biochar product.

FIG. 16 is a block flow diagram of a process for converting biosolidsinto biochar, using a pyrolysis reaction system according to embodimentsof the invention.

FIG. 17 is a SEM image of biochar produced by isothermally pyrolysing abiosolid feed at 500° C. in Example 1.

FIG. 18 is a SEM image of biochar produced by isothermally pyrolysing abiosolid feed at 600° C. in Example 1.

FIG. 19 is a SEM image of biochar produced by isothermally pyrolysing abiosolid feed at 700° C. in Example 1.

FIG. 20 is a SEM image of biochar produced by isothermally pyrolysing abiosolid feed at 800° C. in Example 1.

FIG. 21 is a SEM image of biochar produced by isothermally pyrolysing abiosolid feed at 900° C. in Example 1.

FIG. 22 depicts the design of a pyrolysis reactor system as modelled inExample 2 and operated in a demonstration-scale integrated pyrolysis andcombustion process in Example 3.

FIGS. 23A-23C depict the flow and mixing of inert gas, introduced to thepyrolysis chamber, and air, introduced to the combustion reactor, in thepyrolysis reactor system depicted in FIG. 22, as modelled withcomputational fluid dynamics simulations.

FIG. 24 is a graph of relevant process variables measured during thecourse of the demonstration-scale integrated pyrolysis and combustionprocess in Example 3.

DETAILED DESCRIPTION

The present invention relates to a pyrolysis reaction system. The systemcomprises a pyrolysis chamber configured to receive a pyrolysableorganic feed via a feed inlet and an inert gas via a gas inlet, and topyrolyse the organic feed in the presence of the inert gas to produce acarbonaceous pyrolysis product and a pyrolysis gas. The pyrolysis gaswill thus combine with the inert gas to form a gas mixture in thepyrolysis chamber. The pyrolysis chamber is configured to discharge thesolid carbonaceous pyrolysis product via a product outlet.

The system further comprises a gas reactor configured to react thepyrolysis gas by combustion and/or carbon deposition. A partitiondefines a boundary between the pyrolysis chamber and the gas reactor,with the partition including a plurality of apertures to provide fluidcommunication between the pyrolysis chamber and the gas reactor.

In operation, the gas mixture flows through the apertures from thepyrolysis chamber to the gas reactor as a result of the higher pressuremaintained in the pyrolysis chamber, thereby providing at least aportion of the pyrolysis gas for reaction in the gas reactor. Inpreferred embodiments, the partition is configured such that, when thetemperature in the gas reactor is higher than the temperature in thepyrolysis chamber, heat transfers from the gas reactor to the pyrolysischamber at least in part by convection through the apertures, therebyproviding at least a portion of the heat of pyrolysis in the pyrolysischamber. The heat transferred by convection through the apertures maysupplement heat conducted through the partition that provides anotherportion of the heat of pyrolysis in the pyrolysis chamber.

The present invention also relates to a method of pyrolysing an organicfeed, for example in a pyrolysis system as described herein. The methodcomprises feeding a pyrolysable organic feed and an inert gas to apyrolysis chamber, and pyrolysing the organic feed to produce a solidcarbonaceous pyrolysis product and a pyrolysis gas. The carbonaceouspyrolysis product is discharged from the pyrolysis chamber, and thepyrolysis gas combines with the inert gas to form a gas mixture in thepyrolysis chamber. This gas mixture flows to a gas reactor through aplurality of apertures in a partition that defines a boundary betweenthe pyrolysis chamber and the gas reactor, due to the higher pressuremaintained in the pyrolysis chamber. The pyrolysis gas reacts in the gasreactor by combustion and/or carbon deposition.

In preferred embodiments, the temperature is greater in the gas reactorthan in the pyrolysis chamber, and heat is transferred from the gasreactor to the pyrolysis chamber at least in part by convection throughthe first apertures, thereby providing at least a portion of the heat ofpyrolysis in the pyrolysis chamber.

The features and advantages of the invention may be better understoodwith an appreciation of the operating principles of certain prior artpyrolysis systems. Pyrolysis system 10, which operates according topreviously disclosed principles, is therefore schematically depicted inFIG. 1. Pyrolysis system 10 comprises pyrolysis chamber 11, configuredto receive a pyrolysable organic feed 12 and inert gas 13. Pyrolysissystem 10 further includes combustion reactor 14 adjacent to pyrolysischamber 11. Impermeable metal partition 15 defines a boundary betweenchamber 11 and combustion reactor 14. Pyrolysis chamber 11 iscylindrical, and the interior reaction zone of combustion reactor 14 isan annulus between outer walls 16 and cylindrical partition 15, asschematically depicted in side view in FIG. 1 and in plan view in FIG.1A.

In use, organic feed 12 is fed to pyrolysis chamber 11 and pyrolyses ata temperature between 350° C. and 750° C. to produce pyrolysis gas(generally comprising components that on cooling would separate into gasand oil fractions) and solid carbonaceous pyrolysis products. Thecarbonaceous products are discharged from pyrolysis chamber 11.Pyrolysis gas 17 is withdrawn from chamber 11 and transported byexternal pipework for combustion in combustion reactor 14 with oxygenintroduced via air stream 18. Flue gas 19 is directed to exhaust system20. At least a portion of the heat of combustion is transferred fromreactor 14 through metallic partition 15 by conduction, thereby drivingthe endothermic pyrolysis reaction in pyrolysis chamber 11.

The present invention in its broadest form may be understood byconsidering pyrolysis systems 30 and 50, depicted in FIGS. 2 and 3respectively. Pyrolysis system 30 comprises pyrolysis chamber 31,configured to receive a pyrolysable organic feed 32 and inert gas 33.Pyrolysis system 30 further includes gas reactor 34 adjacent topyrolysis chamber 31. In system 30, gas reactor 34 is a combustionreactor. Partition 35 defines a boundary between chamber 31 and gasreactor 34. Optionally, pyrolysis chamber 31 is cylindrical, and theinterior reaction zone of gas reactor 34 is an annulus between outerwalls 36 and cylindrical partition 35, as schematically depicted in sideview in FIG. 2 and in plan view in FIG. 2A. However, other adjacentreactor configurations may be adopted without departing from the scopeof the invention.

Partition 35 is preferably made of a thermally conductive material(typically metal) and includes a plurality of apertures 41 providingfluid communication between pyrolysis chamber 31 and gas reactor 34.

In use, organic feed 32 is fed to pyrolysis chamber 31 and pyrolyses ata conventional pyrolysis temperature, such as between 350° C. and 750°C. (depending on the feed) in the presence of inert gas 33 to producepyrolysis gas and solid carbonaceous pyrolysis products. Thecarbonaceous products are discharged from pyrolysis chamber 31 viaproduct outlet 44. The pyrolysis gas combines with inert gas 33 to forma gas mixture in chamber 51.

This gas mixture flows through apertures 41 in partition 35 and combustsin gas reactor 34 in the presence of air 38. The resulting temperaturein the combustion reaction zone is controlled to be greater than that inthe pyrolysis reaction zone in chamber 31, typically by about 50 to 300°C., or 100 to 200° C. Partition 35, and in particular the distributionand size of apertures 41 therein, is configured such that a pressuredifferential is maintained between pyrolysis chamber 31 and gas reactor34, and the resulting flow velocity of the gas mixture through theapertures is sufficient to prevent or suitably limit ingress of oxygeninto pyrolysis chamber 34. It will be appreciated that completeexclusion of oxygen may not be required in all embodiments, providedthat the oxygen content in pyrolysis chamber 34 is low enough to alloweffective pyrolysis of the feed.

As a result of the higher temperature in gas reactor 34 due tocombustion, heat is transferred in the opposite direction throughpartition 35, i.e. from gas reactor 34 to pyrolysis chamber 31. Thisheat transfer occurs both by conduction through the thermally conductivepartition material and by convection through apertures 41, therebyproviding at least a portion of the heat necessary to drive theendothermic pyrolysis reaction in chamber 31.

Heat transfer through partition 35 is highly efficient as a result ofthe combined convective and conductive heat transfer modes, as will befurther described hereafter. Moreover, the heat of combustiontransferred from gas reactor 34 is generally sufficient to provide theheat of pyrolysis in pyrolysis chamber 31, such that an external energyinput into the process is not required.

Inert gas 33 may optionally include a portion of hot flue gas 39withdrawn from combustion reactor 34, given the depletion of oxygenresulting from combustion. This may advantageously further improvetransfer of the heat of combustion from combustion reactor 34 topyrolysis chamber 31, and potentially obviate the need for an externalsupply of inert gas. Fan 42 (alternatively a blower or compressor) isused to pressurise inert gas feed 33 into chamber 31, thereby ensuringthat the pressure in pyrolysis chamber 34 is suitably higher than in gasreactor 34. However, inert gas 33 may additionally, or alternatively,include at least a component of non-reactive gas 43, such as N₂ or CO₂.In the broadest conceptualisation of the invention, the composition andsource of inert gas 33 is not considered to be particularly limited,provided that its oxygen content is suitably low to allow pyrolysis ofthe feed in chamber 31.

Pyrolysis system 50, schematically depicted in FIG. 3, comprisespyrolysis chamber 51, configured to receive a pyrolysable organic feed52 and inert gas 53. Pyrolysis system 50 further includes gas reactor 54adjacent to pyrolysis chamber 51. In the case of system 50, gas reactor54 is a carbon deposition reactor, and thus contains catalyst (orcatalyst based support material) 60 for catalysing the formation ofcarbonaceous deposition products, such as carbon fiber or carbonnanomaterials, from pyrolysis gas. As depicted in FIG. 3, catalyst 60may be present on monolithic support. Alternatively, catalyst 60 may bea particulate catalyst which is fluidised or packed in gas reactor 54.

Partition 55 defines a boundary between chamber 51 and gas reactor 54.Pyrolysis chamber 51 and gas reactor 54 may optionally have cylindricaland annular reaction zones, respectively, as discussed herein forpyrolysis system 30. Partition 55 is preferably made of a thermallyconductive material (typically metal) and includes a plurality ofapertures 61 providing fluid communication between pyrolysis chamber 51and gas reactor 54.

In use, organic feed 52 is fed to pyrolysis chamber 51 and pyrolyses ata conventional pyrolysis temperature in the presence of inert gas 53 toproduce pyrolysis gas and solid carbonaceous pyrolysis products. Thecarbonaceous products are discharged from pyrolysis chamber 51 viaproduct outlet 62. The pyrolysis gas combines with inert gas 53 to forma gas mixture.

This gas mixture flows through apertures 61 in partition 55, and thepyrolysis gas therein reacts on catalyst 60 to form carbonaceousdeposition products. The temperature in the carbon deposition reactionzone is maintained at a higher temperature than that in the pyrolysisreaction zone of chamber 51, preferably a temperature between about 600°C. and 1000° C., such as between 700° C. and 900° C., as is generallyrequired to produce high quality carbonaceous products by catalyticcarbon deposition. It will be appreciated that heat must be provided togas reactor 54, since carbon deposition is also an endothermic reaction.In its broadest conceptualisation, this heat may be provided by anysuitable means, including with electrical heating elements,steam-powered heat exchangers etc. However, in preferred embodiments (aswill be described in greater detail hereafter), the heat is provided bycombustion of a portion of the pyrolysis gas and/or the solidcarbonaceous pyrolysis products produced in the process, for example ina further reactor adjacent to gas reactor 54. In such cases, thetemperature in the combustion reaction zone is controlled to be greaterthan that in the carbon deposition reaction zone in chamber 54,typically by about 100 to 200° C.

Partition 55, and in particular the distribution and size of apertures61 therein, is configured such that a pressure differential ismaintained between pyrolysis chamber 51 and gas reactor 54, and theresulting flow velocity of the gas mixture through the apertures istypically sufficient to prevent or suitably limit reverse flow of gasesinto pyrolysis chamber 54. Moreover, apertures 61 in partition 55 aresufficiently small, or otherwise suitably designed to retain solids inpyrolysis chamber 51, thereby preventing contamination of thecarbonaceous deposition products.

As a result of the higher temperature in gas reactor 54, heat istransferred in the opposite direction through partition 55, i.e. fromgas reactor 54 to pyrolysis chamber 51. This heat transfer occurs bothby conduction through the thermally conductive partition material and byconvection through apertures 61, thereby providing at least a portion ofthe heat necessary to drive the endothermic pyrolysis reaction inchamber 51. Heat transfer through partition 55 is highly efficient as aresult of the combined convective and conductive heat transfer modes.

Pyrolysis Reactions

Pyrolysis reaction systems according to the invention include apyrolysis chamber for conducting a pyrolysis reaction of a pyrolysableorganic feed. Industrial pyrolysis reactions are typically performed at350-750° C., depending on the feed and the target products, and thepyrolysis chamber may be suitably configured to operate in thistemperature range. Pyrolysis reactions generally produce a mixture ofproducts, which on removal and cooling include solid carbonaceousproducts (char), an oil fraction and a gas fraction, which havedifferent applications in the production of energy, chemicals and fuels.The fractions of gas, oil and char produced as primary products in apyrolysis process also vary with the heating rate, temperature andfeedstock, and pyrolysis process may be classified accordingly intothree process types: slow pyrolysis, fast pyrolysis and flash pyrolysis.Slow pyrolysis generally produces more char, fast pyrolysis producesmore oil fraction and flash pyrolysis produces more gas fraction.

It will be appreciated that the oil product fraction of the pyrolysisreaction is substantially in vapour form when produced at the highreaction temperatures of pyrolysis. Accordingly, where the presentdisclosure refers to the production of a “pyrolysis gas”, or its furtherreaction by combustion and/or carbon deposition in the pyrolysisreaction system or method of the invention, the “pyrolysis gas” is to beunderstood to include both the gas fraction and the vaporised oilfraction.

In embodiments of the invention where pyrolysis char is the primaryproduct, the pyrolysis process may preferably be a slow pyrolysisprocess. In embodiments of the invention where carbon depositionproducts, produced by catalytic decomposition of gaseous pyrolysisproducts, are the primary product of the process, the pyrolysis processmay either be a slow or a fast pyrolysis process. The heating rate ofthe organic feed in the pyrolysis chamber, which affects the primarypyrolysis selectivity, may be controlled by conventional means,including by controlling the temperature in the reactor, and therelative flow rates of organic feed and inert gas.

The invention is applicable to a wide range of solid pyrolysable organicfeeds, including 1) waste such as plastics, tyres or any other solidhydrocarbon-containing waste or their blends; 2) biomass such as wood,straw, coffee husk and any type of biomass materials; 3) coal such asanthracite, bituminous, sub-bituminous, lignite or any other coalblends; 4) dried algae; 5) biosolids or sewage sludge; 6) food-waste; 7)any type of solid organic or inorganic human waste; 8) biomass wastesuch as green waste or agricultural residue or their blends and 9)hybrid inorganic and organic waste such as municipal solid waste. Forthe avoidance of doubt, the term “pyrolysable organic feed” as usedherein refers to any feed that contains at least a portion of anorganic, carbon-containing material from any source, includingsynthetic, mineral and bio-based sources, that can be pyrolysed toproduce pyrolysis products.

The reaction temperature in the pyrolysis chamber may depend on thenature of the pyrolysable organic feed. Where the feed is a wasteplastic, for example, a relatively low temperature, such as 250° C. to400° C., may be appropriate. Where the feed is biomass, for examplebiosolids derived from sewage, a relatively higher reaction temperature,such as 400° C. to 750° C., may be preferred.

Pyrolysis is an endothermic reaction, and thus requires an input ofenergy, i.e the heat (or enthalpy) of pyrolysis. In at least someembodiments, the required energy input is provided at least in part, andpreferably entirely, by sacrificial combustion of one or more of thepyrolysis product fractions. While this concept has been practiced incertain prior art designs, improved heat transfer from the combustionzone into the pyrolysis chamber is an advantage provided by at leastsome embodiments of the present invention, as will be described ingreater detail hereafter.

Suitable residence times of solids in the pyrolysis chamber may be from10 minutes to one hour, for example 25 to 30 minutes. Suitable pressuresin the pyrolysis chamber may be between 1 and 10 bar, for examplebetween 1 and 3 bar.

Pyrolysis according to the invention is performed in the presence of aninert gas, which is fed to pyrolysis chamber and flows out of thepyrolysis chamber through the apertures in combination with pyrolysisgas product. The flow of inert gas contributes to the pressuredifferential between the pyrolysis chamber and the gas reactor, which isrequired to prevent or substantially limit an unwanted reverse flow ofgases through the apertures. In some embodiments, the inert gas issufficiently hot that it also contributes a portion of the heat requiredto drive pyrolysis. In some embodiments, the organic feed and solidpyrolysis products thereof are fluidised by the flow of inert gas. Thismay advantageously improve mixing and heat transfer in the pyrolysischamber.

The inert gas should generally have a low oxygen content, such as lessthan 4 weight %, or less than 2 weight %, since desirable pyrolysisreaction selectivity is obtained through endothermic cracking reactionsin the absence of oxidants. However, it is not necessarily required thatoxygen is completely excluded. In certain embodiments of the invention,the inert gas includes as at least a component a combustion flue gas,which contains some residual oxygen. The advantages provided by the useof such a gas, for example through heat integration and/or the reductionin consumption of an external inert gas supply, may outweigh thedisadvantages of introducing some oxygen to pyrolysis in certainembodiments.

Partitions

Pyrolysis reaction systems according to the invention include apartition that defines a boundary between a pyrolysis chamber and anadjacent gas reactor. The partition includes a plurality of apertures toprovide fluid communication between the pyrolysis chamber and the gasreactor. In some embodiments, a similar partition is also presentbetween the gas reactor and an adjacent combustion reactor, as will bedescribed hereafter.

The size, number and distribution of apertures in the partition are suchthat a pressure differential is maintained between the pyrolysis chamberand the adjacent gas reactor during operation. A suitable configurationof apertures will thus depend in part on the total flow rate of gasrequired to flow through the partition in operation. The target pressuredifferential, and resulting gas velocity through the apertures, shouldpreferably be sufficient to prevent or suitably limit reverse flow ofgas into the pyrolysis chamber. The apertures should preferably also besufficiently small and suitably designed and/or located within thepartition to exclude solids from the gas mixture flowing into the gasreactor. For example, if the pyrolysis chamber is configured to fluidisesolids in the inert gas, it may be preferred that the apertures arelocated above the fluidisation zone of the pyrolysis chamber. However,the apertures should preferably be sufficient in number and location toallow transfer of heat through the partition by convection, therebyproviding improved heat transfer from the gas reactor to the pyrolysischamber.

With the benefit of this disclosure, a suitable size, number anddistribution of apertures in the partition may be determined withoutundue burden by the skilled person for any particular application,having regard for the principles of the invention. In some embodiments,the size of the apertures in the partition is less than 20 mm, such asbetween 2 mm and 5 mm. In some embodiments, the total opening area ofall the apertures in the partition is at least 50%, such as betweenabout 50% and 90%, of the boundary area defined by the partition betweenthe gas reactor and the pyrolysis chamber.

The partition may be in the form of a wire mesh or a perforated screen.In other embodiments, the partition may comprise plates with fins,bubble caps or other three-dimensionally structured features whichadvantageously further increase the heat transfer across the partitionas a result of increased partition surface area. The material ofconstruction may suitably be SS253MA, SS316L or any other hightemperature alloy or quartz which can withstand the high temperaturesrequired.

The partition with apertures may provide advantageously improved heattransfer, as discussed in greater detail below. Moreover, other benefitssuch as reduced weight and cost, for example via use of a simple meshpartition, may be provided. In some embodiments, the complexity and/oroperability of the pyrolysis systems may be improved, since hot,unstable pyrolysis gas need not be piped externally from the pyrolysischamber to the gas reaction chamber. In some embodiments, the partitionsmay be advantageously removable for cleaning and maintenance, forexample via a releasable means of securing the partitions in place, suchas bolting. In some embodiments, the pyrolysis systems according to theinvention may provide improved flexibility in operation, due to the useof removable and reconfigurable partitions. For example, the samepyrolysis reaction system may be configured suitably for operation inthe mode depicted in FIG. 2, and then reconfigured to operate in themode depicted in FIG. 3. This may be done, for example by fitting anadditional partition as described hereafter with reference to FIG. 10below.

Partition Design for Heat Transfer

In at least some embodiments of the invention, heat transfer is providedacross the aperture-containing partition that separates the hightemperature gas reactor from the lower temperature pyrolysis chamber (asgenerally represented by partitions 35 and 55 depicted in FIGS. 2 and3), compared with a corresponding impermeable partition (for example,partition 15 depicted in FIG. 1). The heat transfer is provided at leastin part by convection through the apertures, and in some embodimentsalso by enhanced conductive heat transfer that occurs through thethermally conductive solid material of the partition.

In one embodiment, partition 63 depicted in plan view in FIG. 4 includesat least a wire mesh comprising metallic wires 64 and apertures 65. Asdepicted in side view in FIG. 4A, gas flows during operation frompyrolysis chamber side 66 to gas reactor side 67, as represented byarrows 68. Heat flows in the opposite direction, from gas reactor side67 to pyrolysis chamber side 66 as a result of the higher temperature inthe gas reactor (whether a combustion or carbon deposition reactor). Theheat is transferred both via conduction through metallic wires 64, asrepresented by arrow 69, and by convection through apertures 65, asrepresented by arrow 69 a.

In another embodiment, partition 70 depicted in FIG. 5 includes at leasta perforated screen comprising plate 71 and apertures 72. Apertures 72are depicted in square pitch 73; however it will be appreciated that atriangular pitch or other arrangement of apertures may similarly beemployed.

In some embodiments, heat transfer across the partition may be furtherimproved by partition designs which increase the surface area of thepartition exposed to the hot gases in the gas reactor, while stillproviding apertures for fluid communication and convective heat transferbetween the pyrolysis chamber and the gas reactor. In the case ofpartition 63 depicted in FIG. 4, for example, the heat transfer area forconductive heat transfer across the partition will decrease, relative toan impermeable partition, due to apertures 65 in the wire mesh.Therefore, in an embodiment, multiple such wire meshes may be stackedtogether in a partition to increase the heat transfer area available forconduction, while still allowing gas flow and convective heat transferthrough the stacked meshes. Thus, the arrangement is made in such a waythat the total heat transfer area is increased significantly, despitethe apertures.

In another embodiment, multiple wire meshes or impermeable plates may bearranged substantially in parallel but apart from each other, in eitherhorizontal or inclined orientations, thereby increasing the heattransfer area on the partition while still creating apertures betweenthe adjacent meshes or plates to provide fluid communication. FIGS. 4Band 4C thus depict partitions 63 b and 63 c respectively, in whichhorizontal plates 64 b/inclined plates 64 c are arranged to provideapertures 65 b/65 c to allow gas flow from pyrolysis chamber side 66b/66 c to gas reactor side 67 b/67 c, respectively. The parallel plate(or mesh) partition provides increased heat transfer area for conductiveheat transfer from gas reactor side 67 b/67 c to pyrolysis chamber side66 b/66 c, respectively. In the case of partition 63 c, the inclinedorientation of stacked plates 64 c minimises the entrainment of solidsin the gas mixture transferred from the pyrolysis chamber to the gasreactor in operation.

Another example of a design to enhance heat transfer area is shown inFIGS. 6 and 6A, which depicts partition 75 comprising at least plate 76in which a plurality of bubble caps 77 are disposed in square pitch 78.As seen in side view in FIG. 6A, each bubble cap 77 comprises hollowprotruding member 80, which inclines upwardly from pyrolysis chamberside 78 to gas reactor side 79. Bubble caps 77 include apertures 81 incap 82 on the gas reactor side to provide the required fluid andconvective heat communication. The external surface area of bubble caps77 provides heat exchange surface area for improved conductive heattransfer from gas reactor side 79 to pyrolysis chamber side 78. Inaddition, the upward inclination of member 80 minimises the entrainmentof solids in the gas mixture flowing towards apertures 81.

In another variation, one or more wire meshes or perforated plates canbe stacked against plate 76, on either side, to increase the heattransfer area. In this case, the pyrolysis gas mixture is stilltransferred from the pyrolysis camber side 78 to gas reactor side 79 bya flow path that includes bubble cap apertures 81.

Another example of a partition design with increased surface area isshown in FIG. 7, which depicts at least a portion of partition 85 inside view. Partition 85 is in the form of corrugated fins, includingprotruding fin members 88 which extend towards gas reactor side 87, andrecessed fin surfaces 92. Apertures 82 are provided both on the frontfin surface of fin members 88 and the recessed fin surfaces 92, suchthat gas flows in use from pyrolysis chamber side 86 to gas reactor side87, as represented by arrows 90. The increased surface area of the findesign provides improved conductive heat transfer from gas reactor side87 to pyrolysis chamber side 86, as represented by arrow 91, in additionto convective heat transfer through apertures 89, represented by arrow91 a.

The fin arrangement may optionally be inclined as well. For example, asdepicted in FIG. 7A, partition 85 a includes a fin arrangement similarto partition 85, but wherein protruding fin members 88 a extend at anupwardly inclining orientation towards gas reactor side 87. The inclinedorientation minimises the entrainment of solids in the gas mixturetransferred through apertures 89 a from pyrolysis chamber side 86 a togas reactor side 87 a in operation.

In some embodiments, the heat transfer across the partitions may befurther improved by movement of the partition relative to the gascombustion reactor, for example by rotating partition 35, as depicted inFIGS. 2 and 2A, about a vertical axis through the centre of gas reactor34.

The inventors consider that improvements of at least 40-50% in heattransfer may be provided with the pyrolysis reaction systems of theinvention compared to some prior art designs. The improved heat transferthus obtained provides a number of potential benefits, including areduction of reactor size, improved temperature control and reactionrate in the endothermic pyrolysis reaction, and thus a higher quality ofcarbonaceous product materials produced. For example, in the embodimentdepicted in FIG. 2, the quantity and quality of carbonaceous material,such as biochar, produced in pyrolysis chamber 31 may be improvedcompared with that produced in pyrolysis chamber 11 of the prior artdesign depicted in FIG. 1. Furthermore, compared with some prior artdesigns, at least some embodiments of the invention provide theadvantage that external energy input is not required, as the heat ofpyrolysis is provided internally by combustion of at least a portion ofthe pyrolysis gas.

Carbon Deposition Reactions

In some embodiments of the invention, as for example described hereinfor system 50 schematically depicted in FIG. 3, the gas reactor adjacentto the pyrolysis chamber is a carbon deposition reactor for producingvarious carbonaceous deposition products such as carbon fiber, carbonnanofiber or other carbon nanomaterials from pyrolysis gas. Carbonnanofibers, for example, can be used in many applications, including inthe automobile industry, the construction industry and in furnituremanufacture. It can also be used for soil amendment, soil remediation,water purification and composites.

As used herein, carbon deposition of pyrolysis gas refers to endothermicreaction of the pyrolysis gas to form carbonaceous solids, for examplecarbon fiber, carbon nanofiber or other carbon nanomaterials. Carbondeposition is generally performed in the presence of a catalyst.Typically, hydrogen is produced as a co-product of carbon deposition.Preferably, carbon deposition is conducted in an inert or reducingatmosphere where carbon deposition reaction predominates over exothermicoxidation reactions such as combustion.

Catalysts for carbon deposition from hydrocarbon-containing gases,including pyrolysis gas, have previously been disclosed in the art, andany such catalysts may in principle be used in the present invention.Suitable catalysts include synthetic metal catalysts, such as nickel,cobalt and copper catalysts. Exemplary catalysts include supportedcobalt catalysts for carbon nanofiber and nanotube formation, asdisclosed in Otsuka et al, J. Phys. Chem. B 2004, 108, 11464-11472;Ni—Cu—MgO catalysts for carbon nanofiber formation, as disclosed inBaker et al, J. Phys. Chem. B 2004, 108, 20273-20277; ahydroxyapatite-supported nickel catalyst for carbon nanofiber formation,as disclosed in Gryglewicz et al, J. Mater. Sci. 2016, 51, 5367-5376;and alumina-supported Ni and Ni—Cu catalysts as disclosed in Zhu et al,Energy & Fuels 2009, 23, 3721-3731.

The catalysts may be may be present on a monolithic support affixedwithin the gas reactor, or alternatively present in particulate form.Particulate catalysts may be packed or fluidised in the gas reactor. Insome embodiments, particulate catalysts are continuously or periodicallyloaded during operation of the pyrolysis system, and continuously orperiodically discharged after a suitable residence time. Suitablecatalyst residence times in this context may be from 5 minutes to anhour, for example about 40 minutes.

Carbon deposition is an endothermic reaction and thus requires heatinput, i.e. of the heat (or enthalpy) of carbon deposition provided at asuitably high temperature. Suitable temperatures for carbon depositionare typically from 600° C. to 1000° C., such as from 700° C. to 900° C.,and the gas reactor may thus be configured in some embodiments tooperate within this range.

Combustion Reactions

In some embodiments of the invention, as for example described hereinfor system 30 schematically depicted in FIG. 2, the gas reactor adjacentto the pyrolysis chamber is a combustion reactor, for combusting atleast a portion of the pyrolysis gas produced in the pyrolysis chamber.At least a portion of this pyrolysis gas flows, as a mixture with theinert gas, through the apertures in the partition separating the gasreactor from the pyrolysis chamber, and combusts in the presence of anoxygen-containing feed (typically air) introduced to the combustionchamber.

In other embodiments of the invention, and in particular in embodimentssuch as system 50 (depicted in FIG. 3) where the gas reactor adjacent tothe pyrolysis chamber is a carbon deposition reactor, a combustionreactor may be provided elsewhere in the pyrolysis system to combust oneor more pyrolysis product fractions produced in the pyrolysis chamber.Such combustion reactors may be configured within the pyrolysis reactionsystem in a number of ways, as will be described hereafter.

In general, the heat of combustion produced in the combustion reactorsis used to supply heat input required for the endothermic pyrolysisand/or carbon deposition reactions, preferably the entire heat inputrequired such that the system is thermally self-sufficient. Optionally,excess heat of combustion may be used to produce steam and/or electricalpower.

The temperature within the combustion reactor may be controlledaccording to known principles, for example by controlling the feed rateof air or by regulating the flow of coolant through a heat-exchanger,e.g. the rate of steam production. The temperature in the combustionreactor may be controlled so as to provide the necessary heat ofreaction in an adjacent endothermic reactor: either the pyrolysischamber or a carbon deposition reactor. For example, the control may beresponsive to a temperature measured in the endothermic reaction zone,so as to maintain a constant or range-bound reaction temperature. Thetemperature in the combustion reactor may in practice be greater thanthe temperature in the neighbouring endothermic reaction zone by about50 to 300° C., or 100 to 200° C. It will be appreciated that, wherecontrol is achieved by regulating the air flow to the combustionreactor, combustion of the pyrolysis gas in the combustion reactor willbe incomplete. Accordingly, a secondary combustion reactor may beprovided to fully combust the residual pyrolysis gas, as will bedescribed in greater detail hereafter.

EMBODIMENTS

It will be appreciated that the pyrolysis system of the invention, forexample as embodied by systems 30 and 50 depicted in FIGS. 2 and 3, hasthus far been described with emphasis on the broadest principles of theinvention. These principles may be applied in a number of differentways, as will now be described.

An embodiment of the invention will thus be described with reference toFIG. 8, which schematically depicts pyrolysis reaction system 100.System 100 comprises cylindrical pyrolysis chamber 102 equipped withfeed inlet 104 through which a pyrolysable organic feed is fed to thecore or bottom of the chamber. The feed is supplied to feed inlet 104using screw feeder 106, or other suitable conveying gears, from hopper108.

Pyrolysis chamber 102 includes gas inlet 110, through which an inert gas112 is fed. Inert gas 112 may include a combustion flue gas component114 having less than 4 mass % O₂ content, a component of non-reactivegas 116 (such as N₂ or CO₂), or a combination thereof. Fan 117 isprovided to pressurise inert gas feed 112 into the chamber 102.Pyrolysis chamber 102 is configured to fluidise the organic feed, andsolid pyrolysis products thereof, in inert gas 112, thus improving massand heat transfer during pyrolysis. Gas distributors (not shown)suitable to distribute the flow of inert gas 110 for fluidisation arethus included at the bottom of chamber 102.

Pyrolysis chamber 102 also includes product outlet 118, for dischargingsolid carbonaceous pyrolysis product 120, in the form of biochar, fromthe chamber. Outlet 118 may be equipped with a screw feeder to conveyproduct 120 from the pyrolysis zone to a discharge location.

Pyrolysis reaction system 100 further comprises gas reactor 130,surrounding pyrolysis chamber 102. The interior reaction zone of gasreactor 130 is an annulus between impermeable cylindrical outer reactorwalls 132 and partition 134, which defines a boundary between chamber102 and gas reactor 130. The cross-sectional configuration of pyrolysischamber 102 and gas reactor 130 can be seen in top view 136,schematically depicted in FIG. 8.

Gas reactor 130 is a combustion reactor for combusting pyrolysis gasproduced in pyrolysis chamber 102, and thus includes port 138 forintroducing hot air 140 and duct 142 for removing combustion flue gas144. As depicted in FIG. 8, port 138 and duct 142 are at the top andbottom of gas reactor 130 respectively, such that the flow of gasesthrough gas reactor 130 in use is downwards. Heat exchanger 146 ispositioned inside gas reactor 102, such that water 148 fed to the heatexchanger during combustion vaporises to form steam 150 for generatingpower in a steam turbine 152.

Partition 134 is in the form of a cylindrical metallic mesh (or otherpartition configuration as disclosed herein), and thus includes aplurality of apertures providing fluid communication between pyrolysischamber 102 and gas reactor 130. The partition and the aperturestherein, are configured such that, in use, gases will flow through thepartition from a higher pressure in pyrolysis chamber 102 to a lowerpressure in gas reactor 130, but heat will flow in the oppositedirection from gas reactor 130 to pyrolysis chamber 102. Partition 134is configured to be rotatable relative to gas reactor 130, about avertical axis through the centre of pyrolysis chamber 102. Rotor 154 isprovided to drive the rotation.

Hot flue gas 144 leaving reactor 130 passes through heat exchanger 156,there exchanging heat with air feed 158. Resultant heated air 160 isthen directed to port 138 for introduction to gas reactor 130 as atleast a component of hot air 140. A portion of cooled flue gas 144 isthen optionally recycled to inlet 110, as combustion flue gas component114 of inert gas 112. The remaining flue gas 144 is directed to anexhaust system 162, where it may be treated by conventional cleaningprocesses (i.e. scrubbing and dust removal to remove aerosols, acids,SOx and NOx) before venting to the atmosphere.

Optionally, a portion of hot flue gas 144 is diverted before heatexchanger 156, and instead directed through a heat exchanger tubepositioned in pyrolysis chamber 102 (not shown). In use, this providesadditional heat for the pyrolysis reaction to supplement the heatflowing directly through partition 134 from gas reactor 130.

In use, a pyrolysable organic feed is fed via feed inlet 104 topyrolysis chamber 102, and fluidised in inert gas 112. At thetemperature (such as between 400° C. to 750° C.) maintained in chamber102, the feed pyrolyses to produce hot pyrolysis gas (generallycomprising components that on cooling would separate into gas andpyrolysis oil fractions) and solid carbonaceous pyrolysis products.After a suitable residence time in chamber 102, carbonaceous pyrolysisproduct 120 is discharged via product outlet 118. The pyrolysis gasproduct combines with inert gas 112 to form a combustible gas mixture,at an elevated pressure of between 1 and 10 bar, for example from 1 to 3bar.

This gas mixture flows through the apertures in partition 134 andcombusts in gas reactor 130 in the presence of air 140, producing anelevated temperature controlled at between 100° C. and 200° C. higher inthe combustion reaction zone than in pyrolysis chamber 102. Heat thusflows from gas reactor 130 to pyrolysis chamber 102 through rotatingpartition 134, both by convection through the apertures and byconduction through the metallic partition material, to drive theendothermic pyrolysis reaction in chamber 102.

Heat transfer through partition 134 is highly efficient, primarily as aresult of the combined convective and conductive heat transfer modes,but further improved by the rotation of partition 134 through the hotcombustion gases in gas reactor 130. The heat of combustion produced ingas reactor 130 is sufficient to provide the heat of pyrolysis inpyrolysis chamber 102, such that external energy input into the processis not required. Moreover, the overall pyrolysis-combustion process issufficiently exothermic for many pyrolysable feeds that excess heat ofcombustion may be used to generate steam in heat exchanger 146, and thuselectrical power in turbine 152. Alternatively, excess pyrolysis gas maybe withdrawn from pyrolysis chamber 102 via a withdrawal pipe (notshown), condensed and used for various purposes such as bio-chemicals orbiofuel production.

The pressure differential maintained between pyrolysis chamber 102 andgas reactor 130 as a result of the design of apertures in partition 134,and the flow velocities of gas mixture through these apertures, aresufficient to prevent or suitably limit ingress of oxygen from reactor130 into pyrolysis chamber 102. It will be appreciated that completeexclusion of oxygen may not be required, provided that the oxygencontent in pyrolysis chamber 102 is low enough to allow effectivepyrolysis of the feed.

Carbonaceous product 120 obtained from this process, which may bebiochar when a biomass feedstock is used, is considered to be ofsuperior quality compared to that from at least some prior art pyrolysisprocesses. The improvement, for example on one or more metrics such asincreased surface area, porosity and improved morphology, is due to theimproved heat transfer in the pyrolysis reaction system 100. It isenvisaged that product 120 may be used to produce activated carbon usingconventional chemical/physical activation methods. Optionally, processunits for activation of product 120 can be integrated into system 100.

A related embodiment of the invention is depicted in FIG. 9, whichschematically depicts pyrolysis reaction system 190. Similarly numbereditems are as described for pyrolysis reaction system 100 with referenceto FIG. 8. In system 190, however, pyrolysis chamber 102 is a rotarykiln type reactor, rotated by rotor 154. Pyrolysable organic feed is fedto the top of pyrolysis chamber 102 through feed inlet 104, and ispyrolysed in a moving bed that progresses under influence of gravity andthe rotation of partition 134 towards product outlet 118, wherecarbonaceous pyrolysis product 120 is discharged. The organic feed andsolid carbonaceous products are retained within pyrolysis chamber 102during pyrolysis by the mesh partition 134, which has suitably smallapertures. However, as described for system 100, the pressured gasmixture in chamber 102, comprising inert gas 112 and pyrolysis gasproduct, flows through the apertures in partition 134 and combusts inthe annular combustion zone of gas reactor 130. Heat of combustion flowsby convection and conduction into pyrolysis chamber 102 through rotatingpartition 134, thereby driving the endothermic pyrolysis reaction.

Another embodiment of the invention will now be described with referenceto FIG. 10, which schematically depicts pyrolysis reaction system 200.System 200 comprises cylindrical pyrolysis chamber 202 equipped withfeed inlet 204 through which a pyrolysable organic feed is fed to thecore or bottom of the chamber. The feed is supplied to feed inlet 204using screw feeder 206, or other suitable conveying gears, from hopper208.

Pyrolysis chamber 202 includes gas inlet 210, through which an inert gas212 is fed. Inert gas 212 may include a combustion flue gas component214, a component of non-reactive gas 216 (such as N₂ or CO₂), or acombination thereof. Fan 217 is provided to pressurise inert gas feed212 into chamber 202. Pyrolysis chamber 202 is configured to fluidisethe organic feed, and solid pyrolysis products thereof, in inert gas212, thus improving mass and heat transfer during pyrolysis. Pyrolysischamber 202 further includes product outlet 218, for discharging solidcarbonaceous pyrolysis product from the chamber for combustion, as willbe described hereafter.

Pyrolysis reaction system 200 further comprises gas reactor 230, whichsurrounds pyrolysis chamber 202. The interior reaction zone of gasreactor 130 is an annulus between cylindrical outer partition 272 andinner partition 234. Inner partition 234 thus defines a boundary betweenpyrolysis chamber 202 and gas reactor 230.

Gas reactor 230 in this embodiment is a carbon deposition reactor forproducing a carbonaceous product from pyrolysis gas produced inpyrolysis chamber 202. At least one monolith 270, which includes acatalyst, is thus affixed in gas reactor 230 to provide a support forthe growth of carbonaceous deposition products, such as carbon fiber orcarbon nanomaterials.

Inner partition 234 is in the form of a cylindrical metallic mesh (orother partition configuration as disclosed herein), and thus includes aplurality of apertures providing fluid communication between pyrolysischamber 202 and gas reactor 230. The partition, and the aperturestherein, are configured such that, in use, gases will flow through thepartition from a higher pressure in pyrolysis chamber 202 to a lowerpressure in gas reactor 230, but heat will flow in the oppositedirection from gas reactor 230 to pyrolysis chamber 202. Partition 234is configured to be rotatable relative to gas reactor 230, about avertical axis through the centre of pyrolysis chamber 202. Rotor 254 isprovided to drive the rotation.

Pyrolysis reaction system 200 further comprises combustion reactor 280,surrounding gas reactor 230. The interior reaction zone of combustionreactor 280 is an annulus between impermeable cylindrical reactor walls282 and outer partition 272. Outer partition 272 thus defines a boundarybetween gas reactor 230 and combustion reactor 280. The cross-sectionalconfiguration of pyrolysis chamber 202, gas reactor 230 and combustionreactor 280 is schematically depicted in FIG. 10A.

Combustion reactor 280 includes port 238 for introducing hot air 240,duct 242 for removing combustion flue gas 244, and ash outlet 247. Asdepicted in FIG. 10, port 138 and duct 142 are at the bottom and top ofcombustion reactor 280 respectively, such that the flow of gases throughcombustion reactor 280 in use is upwards. Combustion reactor 280 alsocomprises solid fuel inlet 245, through which solid carbonaceouspyrolysis product from pyrolysis reactor 202 is discharged. A screwfeeder or other suitable conveying gears may be provided to convey thepyrolysis product via a pipe from outlet 218 of pyrolysis reactor 202 toinlet 245 of combustion reactor 280. Once discharged via inlet 245,solid pyrolysis product may be fluidised in the upward flow of hot air240 for improved mass and heat transfer.

Outer partition 272 is also in the form of a cylindrical metallic mesh,perforated screen (or other suitable partition configuration disclosedherein), and thus includes a plurality of apertures providing fluidcommunication between gas reactor 230 and combustion reactor 280. Thepartition, and the apertures therein, are configured such that, in use,gases will flow through the partition from a higher pressure in gasreactor 230 to a lower pressure in combustion reactor 280, but heat willflow in the opposite direction from combustion reactor 280 to gasreactor 230, as will be explained hereafter.

Combustion reactor 280 is thus configured to combust both solidpyrolysis product discharged from pyrolysis reactor 202, and unreactedpyrolysis gas that flows from gas reactor 230 through the apertures ofouter partition 272.

A portion of hot flue gas 244 leaving combustion reactor 280 passesthrough heat exchanger 256, there exchanging heat with air feed 258.Resultant heated air 240 is directed to port 238 for introduction tocombustion reactor 230. A portion of the cooled flue gas 244 is thenoptionally recycled to inlet 210, as a component of inert gas 212. Theremaining cooled flue gas 244 is sent to exhaust system 262.

Another portion of hot flue gas 244 is directed through a heat exchangertube which passes through monolith 270 in gas reactor 230, and then sentto exhaust system 262. In use, this provides additional localisedheating for the carbon deposition reaction taking place on the catalystof monolith 270, supplementing the heat flowing directly throughpartition 272 from combustion reactor 280. Optionally, still anotherportion of hot flue gas 244 is fed as gas feed 281 into gas reactor 230,using fan 284 to pressurise the gas to the required pressure.Optionally, yet another portion of hot flue gas 244 is directed througha heat exchanger tube positioned in pyrolysis chamber 202 (not shown),to supplement the heat flowing directly through partition 234 from gasreactor 230.

In use, a pyrolysable organic feed is fed via feed inlet 204 topyrolysis chamber 202, and fluidised in inert gas 212. At thetemperatures of between 400° C. to 750° C. maintained in the chamber202, the feed pyrolyses to produce pyrolysis gas and carbonaceouspyrolysis products. After a suitable residence time in chamber 202,carbonaceous pyrolysis product is discharged via outlet 218 intocombustion reactor 280. The pyrolysis gas product combines with inertgas 212 to form a gas mixture in chamber 202, at an elevated pressure ofbetween 1 bar and 10 bar, such as from 1 bar to 3 bar.

This gas mixture flows through the apertures in partition 234 as aresult of the lower pressure in gas reactor 230, and a portion of thepyrolysis gas therein reacts on monolith 270. The temperature in gasreactor 230 is maintained at a higher temperature than in chamber 202,such as between 700° C. and 800° C., to allow the deposition ofcarbonaceous products on the heated monolith catalyst. As a result ofthe higher temperature maintained in gas reactor 230, heat flows topyrolysis chamber 202 through rotating partition 234, both by convectionthrough the apertures and by conduction through the metallic partitionmaterial, thereby driving the endothermic pyrolysis reaction in chamber202.

The pressure differential maintained between pyrolysis chamber 202 andgas reactor 230 as a result of the design of apertures in partition 234,and the flow velocities of gas mixture through these apertures, issufficient to prevent or suitably limit ingress of gases from gasreactor 230 into pyrolysis chamber 202. Moreover, the apertures aresufficiently small to ensure that solids are retained in pyrolysischamber 202, thereby preventing contamination of the depositedcarbonaceous materials.

After a suitable residence time to allow carbon deposition, the gasmixture in gas reactor 230, including inert gas 212 and unreactedpyrolysis gas, flows through the apertures in partition 272 to the stilllower reaction pressure maintained in combustion reactor 280. Thepyrolysis gas and the carbonaceous product discharged via inlet 245 bothcombust in combustion reactor 280 in the presence of air 240, producingan elevated temperature controlled between 900° C. and 1000° C. in thecombustion reaction zone. Heat thus flows from combustion reactor 280 togas reactor 230 through partition 272, both by convection through theapertures and by conduction through the metallic partition material, todrive the endothermic carbon deposition reaction in gas reactor 230, andindirectly the endothermic pyrolysis reaction in pyrolysis reactor 202.

Heat transfer through partition 272 is highly efficient, as a result ofthe combined convective and conductive heat transfer modes. The heat ofcombustion produced in combustion reactor 280 is sufficient to provideboth the heat of carbon deposition in gas reactor 230 and the heat ofpyrolysis in pyrolysis chamber 102, such that an external energy inputinto the process is not required. Optionally, excess heat of combustionmay be used to generate steam (not shown).

The pressure differential maintained between gas reactor 230 andcombustion reactor 280 as a result of the design of apertures inpartition 272, and the resulting flow velocities of gas mixture throughthese apertures, is sufficient to prevent or suitably limit ingress ofoxygen from combustion reactor 280 into gas reactor 230.

The carbon deposition products, such as carbon fibers, carbon nanofibersand the like, are expected to be of superior quality compared to thosefrom at least some prior art pyrolysis processes. This improvement, forexample on one or more metrics such as increased surface area, porosityand improved morphology, is due to improved heat transfer in thepyrolysis reaction system 200. It is envisaged that additional processsteps may be undertaken to separate or further activate the carbonaceousproducts, and that process units for such purposes can be coupled withthe existing units in an integrated manner.

In a related embodiment, and with continued reference to FIG. 10,monolith 270 with supported catalyst is omitted from system 200. Insteada particulate catalyst for carbon deposition is added to gas reactor 230in use, and fluidised with gas feed 281, which comprises flue gas 244and/or a non-reactive gas such as N₂. Carbonaceous products thus depositon the fluidised catalyst particles. The catalyst particles may becontinuously loaded, and carbonaceous products unloaded after a suitableresidence time, via a catalyst feed inlet and carbon product outlet ingas reactor 230 (not shown).

Another embodiment of the invention will now be described with referenceto FIG. 11, which schematically depicts pyrolysis reaction system 300.System 300 operates according to similar principles as system 200, andsimilarly numbered items are as described for pyrolysis reaction system200 shown in FIG. 10.

In system 300, however, pyrolysis chamber 202 is a rotary kiln typereactor. Pyrolysable organic feed is fed to the top of pyrolysis chamber202 through feed inlet 204, and is pyrolysed in a moving bed thatprogresses under influence of gravity and the rotation of partition 234towards product outlet 218, where carbonaceous pyrolysis product isdischarged. The organic feed and solid carbonaceous products areretained within pyrolysis chamber 202 during pyrolysis by the mesh ofpartition 234, which has suitably small apertures.

In use, and as described for system 200, the pressurised gas mixture inchamber 202, comprising inert gas 212 and pyrolysis gas product, flowsthrough the apertures in inner partition 234 and reacts to formcarbonaceous deposition products on monolith 270 located gas reactor230. As a result of the higher temperature maintained in gas reactor230, heat flows by convection and conduction into pyrolysis chamber 202through rotating partition 134, thereby driving the endothermicpyrolysis reaction.

System 300 includes combustion reactor 280, which surrounds gas reactor230 and is separated therefrom by outer partition 272, as also presentin system 200. However, differently from system 200, system 300additionally includes further combustion reactor 281 as a physicallyseparate unit. Combustion reactor 281 includes port 283 for introducinghot air 240, duct 284 for removing combustion flue gas 285, and ashoutlet 286.

Combustion reactor 281 also includes solid fuel inlet 287, through whichcarbonaceous pyrolysis product from pyrolysis reactor 202 is discharged.A screw feeder or other suitable conveying gears may be provided toconvey the pyrolysis product via a pipe from outlet 218 of pyrolysisreactor 202 to inlet 287 of combustion reactor 281. Once discharged viainlet 287, the solid pyrolysis product may be fluidised in the upwardflow of hot air 240 for improved mass and heat transfer duringcombustion.

Combustion reactor 281 includes cyclone 288 for returning solidsentrained in combustion flue gas 285 to the combustion zone. Hot fluegas 285 is fed from the cyclone to combustion reactor 280 via port 289.

In use, the gas mixture in gas reactor 230, including inert gas 212 andunreacted pyrolysis gas, flows through the apertures in outer partition272 into combustion reactor 280, as described for system 200. Thepyrolysis gas combusts there in the presence of oxygen provided by airfeed 290 and/or residual oxygen in flue gas 285. The sensible heatprovided in flue gas 285, and the heat produced by the furthercombustion taking place in combustion reactor 280, produces an elevatedtemperature controlled at between 900° C. and 100° C. in the combustionreaction zone of reactor 280. Heat thus flows from combustion reactor280 to gas reactor 230 through partition 272, both by convection throughthe apertures and by conduction through the metallic partition material,to drive the endothermic carbon deposition reaction in gas reactor 230,and indirectly the endothermic pyrolysis reaction in pyrolysis reactor202.

Another embodiment of the invention will now be described with referenceto FIG. 12, which schematically depicts pyrolysis reaction system 400.System 400 comprises pyrolysis chamber 402, which is a rotary kiln typereactor rotated by a rotor (not shown). Pyrolysable organic feed is fedto the top of pyrolysis chamber 402 through feed inlet 404, using screwfeeder 406 from hopper 408.

Pyrolysis chamber 402 includes gas inlet 410, through which an inert gas412 is fed at a flow rate and pressure sufficient to provide therequired pressure in chamber 402. Pyrolysis chamber 402 further includesgas duct 420 for flowing gas mixture 460 out of the chamber, and productoutlet 418 for discharging solid carbonaceous pyrolysis product from thechamber for combustion, as will be described hereafter.

Pyrolysis reaction system 400 further comprises gas reactor 430,surrounding pyrolysis chamber 402. The interior reaction zone of gasreactor 430 is an annulus between impermeable cylindrical outer reactorwalls 432 and partition 434, which defines a boundary between chamber402 and gas reactor 430. Gas reactor 430 is gas combustion reactor forcombusting a portion of the pyrolysis gas produced in pyrolysis chamber402, and thus includes port 489 for introducing hot oxygen-containinggas 488 and duct 442 for removing combustion flue gas 444.

Partition 434 is in the form of a cylindrical metallic mesh (or otherpartition configuration as disclosed herein), and thus includes aplurality of apertures providing fluid communication between pyrolysischamber 402 and gas reactor 430. The partition, and the aperturestherein, are configured such that, in use, gases will flow through thepartition from a higher pressure in pyrolysis chamber 402 to a lowerpressure in gas reactor 430, but heat will flow in the oppositedirection from gas reactor 430 to pyrolysis chamber 402.

Hot flue gas 444 leaving gas reactor 430 passes through heat exchanger456, there exchanging heat with air feed 458 to produce hot air 459.Cooled flue gas 444 is sent from heat exchanger 456 to exhaust system462.

System 400 further comprises carbon deposition reactor 480 andcombustion reactor 481, as separate process units from chamber 402/gasreactor 430. Carbon deposition reactor 480 comprises impermeablecylindrical wall 450, port 483 for introducing gas mixture 460 frompyrolysis chamber 402, duct 484 for removing off-gas 485, catalyst feedinlet 452 and carbon product outlet 486.

Combustion reactor 481 surrounds carbon deposition reactor 480, with itsinterior reaction zone being an annulus between cylindrical outer wall451 and cylindrical inner wall 450. Cylindrical wall 450 thus defines aboundary between combustion reactor 481 and carbon deposition reactor480, through which heat may flow via conduction.

Combustion reactor 481 includes port 475 for introducing hot air 459,gas inlet 461 for introducing combustible off-gas 485 from carbondeposition reactor 480, and an ash outlet (not shown). Combustionreactor 481 also includes solid fuel inlet 487, through whichcarbonaceous pyrolysis product from pyrolysis reactor 402 is discharged.A screw feeder is provided to convey the pyrolysis product via a pipefrom outlet 418 of pyrolysis reactor 402 to inlet 487 of combustionreactor 481. Once discharged via inlet 487, the solid pyrolysis productmay be fluidised in the upward flow of hot air 459 for improved mass andheat transfer during combustion. Combustion reactor 481 also includesduct 463 for removing hot flue gas 473. Flue gas 473 is combined withair feed 490 (optionally a diverted portion of hot air 459) and fed togas reactor 430 as hot oxygen-containing gas 488 via port 489.

In use, a pyrolysable organic feed is fed via feed inlet 404 topyrolysis chamber 402. At the temperature of between 400° C. to 750° C.maintained in the chamber 402, the feed is pyrolysed in a moving bedthat progresses under influence of gravity and the rotation of partition434 towards product outlet 418, where carbonaceous pyrolysis product isdischarged into combustion reactor 481. The organic feed and solidcarbonaceous products are retained within pyrolysis chamber 402 duringpyrolysis by the mesh partition 434, which has suitably small apertures.The pyrolysis gas product combines with inert gas 412 to form a gasmixture in chamber 402, at an elevated pressure of between 1 bar and 10bar, such as from 1 bar to 3 bar.

A portion of this gas mixture flows through the apertures in partition434 and combusts in gas reactor 430 in the presence of hotoxygen-containing gas 488 fed via port 489. The sensible heat providedin gas 488, and the heat produced by the combustion taking place in gasreactor 430, produces an elevated temperature controlled at between 50°C. and 300° C. higher in the combustion reaction zone than in pyrolysischamber 402. Heat thus flows from gas reactor 430 to pyrolysis chamber402 through rotating partition 434, both by convection through theapertures and by conduction through the metallic partition material, todrive the endothermic pyrolysis reaction in chamber 402.

In this embodiment, another portion 460 of the gas mixture in pyrolysischamber 402 flows via gas duct 420 and is introduced through port 483into carbon deposition reactor 480. A particulate catalyst is also addedto carbon deposition reactor 480, via catalyst feed inlet 452. At thecontrolled temperature of between 700° C. and 800° C. maintained in thereactor, carbonaceous products deposit on the catalyst particles byreaction of the pyrolysis gas. The carbonaceous products are unloadedvia carbon product outlet 486 after a suitable catalyst residence timein carbon deposition reactor 480.

After a suitable gas residence time to allow carbon deposition, the gasmixture in carbon deposition reactor 480, including inert gas 412 andunreacted pyrolysis gas, flows through duct 484 as off-gas 485. Off-gas485 is then fed via gas inlet 461 to combustion reactor 481. Thepyrolysis gas therein, and the carbonaceous pyrolysis product dischargedvia inlet 487, both combust in combustion reactor 481 in the presence ofair 459, producing an elevated temperature controlled between 900° C.and 1200° C. in the combustion reaction zone. Heat thus flows byconduction from combustion reactor 481 to carbon deposition reactor 480through wall 450, thereby driving the endothermic carbon depositionreaction. Hot flue gas 473 is removed from combustion reactor 481 viaduct 463, combined with air feed 490 and fed to gas reactor 430, asdescribed herein.

Another embodiment of the invention will now be described with referenceto FIG. 13, which schematically depicts pyrolysis reaction system 500.System 500 comprises cylindrical pyrolysis chamber 502 equipped withfeed inlet 504 through which a pyrolysable organic feed is fed to thecore or bottom of the chamber. The feed is supplied to feed inlet 504using screw feeder 506 from hopper 508.

Pyrolysis chamber 502 includes gas inlet 510, through which inert gas512 is fed. Inert gas 512 may include a combustion flue gas component514, a component of non-reactive gas 516 (such as N₂ or CO₂), or acombination thereof. Fan 517 is provided to pressurise inert gas feed512 into chamber 502. Pyrolysis chamber 502 is configured to fluidisethe organic feed, and solid pyrolysis products thereof, in inert gas512, thus improving mass and heat transfer during pyrolysis. Pyrolysischamber 502 further includes product outlet 518, for discharging solidcarbonaceous pyrolysis product from the chamber for combustion, as willbe described hereafter.

Pyrolysis reaction system 500 further comprises cylindrical gas reactor530, which in this embodiment is positioned directly above pyrolysischamber 502. Horizontal partition 534 separates and defines a boundarybetween pyrolysis chamber 502 and gas reactor 530. Cylindrical partition572 defines the periphery of both pyrolysis chamber 502 and gas reactor530.

Gas reactor 530 in this embodiment is a carbon deposition reactor forproducing a carbonaceous product from the pyrolysis gas produced inpyrolysis chamber 202. Gas reactor 530 includes catalyst feed inlet 552and carbon product outlet 586.

Partition 534 is in the form of a planar metallic mesh (or otherpartition configuration disclosed herein), and thus includes a pluralityof apertures providing fluid communication between pyrolysis chamber 502and gas reactor 530. The partition, and the apertures therein, areconfigured such that, in use, gases will flow through the partition froma higher pressure in pyrolysis chamber 502 to a lower pressure in gasreactor 530. Heat flows in the opposite direction from gas reactor 530to pyrolysis chamber 502, by both conduction and convection.

Pyrolysis reaction system 500 further comprises combustion reactor 580,surrounding both pyrolysis chamber 502 and gas reactor 530. The interiorreaction zone of combustion reactor 580 is an annulus betweenimpermeable cylindrical reactor walls 582 and cylindrical partition 572.Horizontal partition 534 optionally divides combustion reactor 580 intofluidly connected lower and upper sub-zones, as depicted in FIG. 13,with the apertures providing a restricted flow of combustion gasesthrough combustion reactor 580 and allowing independent control oftemperatures and gas compositions in the sub-zones. Alternatively,partition 534 does not extend outwardly beyond cylindrical partition572, such that uninhibited flow of gases is permitted through combustionreactor 580.

Combustion reactor 580 includes port 538 for introducing hot air 540,duct 542 for removing combustion flue gas 544, and an ash outlet (notshown). As depicted in FIG. 13, port 538 and duct 542 are at the bottomand top of combustion reactor 580 respectively, such that the flow ofgases through combustion reactor 580 is upwards. Combustion reactor 580also comprises solid fuel inlet 545, through which carbonaceouspyrolysis product from pyrolysis reactor 502 is discharged. A screwfeeder is provided to convey the pyrolysis product via a pipe fromoutlet 518 of pyrolysis reactor 502 to inlet 545 of combustion reactor580. Once discharged via inlet 545, solid pyrolysis product may befluidised in the upward flow of hot air 540 for improved mass and heattransfer during combustion.

Cylindrical partition 572 is also in the form of a metallic mesh,perforated screen or the like, and thus includes a plurality ofapertures providing fluid communication between combustion reactor 580and each of pyrolysis chamber 502 and gas reactor 530. The partition,and the apertures therein, are configured such that, in use, gases willflow through the partition from the higher pressures in pyrolysischamber 502 and gas reactor 530 to the lower pressure maintained incombustion reactor 580, but heat is able to flow in the oppositedirection from combustion reactor 580 to each of pyrolysis chamber 502and gas reactor 530, as will be explained hereafter.

Combustion reactor 580 is thus configured to combust both solidpyrolysis product discharged from pyrolysis reactor 502, and unreactedpyrolysis gas that flows from pyrolysis chamber 502 and gas reactor 530through the apertures of cylindrical partition 572.

Hot flue gas 544 leaving combustion reactor 580 passes through heatexchanger 556, there exchanging heat with air feed 558. Resultant heatedair 540 is directed to port 538 for introduction to combustion reactor530. A portion of the cooled flue gas 544 is then optionally recycled toinlet 510, as combustion flue gas component 514 of inert gas 512. Theremaining cooled flue gas 544 is sent to exhaust system 562.

Optionally, a portion of hot flue gas 544 is directed through one ormore heat exchanger tubes which pass through pyrolysis chamber 502and/or gas reactor 530 (not shown). In use, this provides additionalheat for the endothermic pyrolysis and/or carbon deposition reactions,supplementing the heat from combustion reactor 280 flowing directly topyrolysis chamber 502 and/or gas reactor 530 through cylindricalpartition 272.

In use, a pyrolysable organic feed is fed via feed inlet 504 topyrolysis chamber 502, and fluidised in inert gas 512. At thetemperature of between 400° C. to 750° C. maintained in the chamber 502,the feed pyrolyses to produce pyrolysis gas and carbonaceous pyrolysisproducts. After a suitable residence time in chamber 502, carbonaceouspyrolysis product is discharged via outlet 518 into combustion reactor580. The pyrolysis gas product combines with inert gas 512 to form a gasmixture in chamber 502, at an elevated pressure of between 1 bar and 10bar, such as from 1 bar to 3 bar.

This gas mixture flows through the apertures in both partitions 534 and572, as a result of the lower pressures in gas reactor 530 andcombustion reactor 580. It will be appreciated that the relativeproportion of flow to gas reactor 530 and combustion reactor 580 may becontrolled by the relative size and abundance of the apertures in thepartitions, and the pressures controlled in the reactors.

A particulate catalyst is added to gas reactor 580 via catalyst feedinlet 552, and fluidised in the gas mixture entering gas reactor 580through partition 534. At the temperature of between 700° C. and 800° C.maintained in the reactor, the pyrolysis gas in the gas mixture reactsby carbon deposition to form carbonaceous products on the catalystparticles. The apertures in partition 534 are sufficiently small toensure that solids are retained in pyrolysis chamber 502, therebypreventing contamination of the deposited carbonaceous materials. Thecarbonaceous products, such as carbon fibers or carbon nanomaterials,are unloaded via carbon product outlet 586 after a suitable catalystresidence time in gas reactor 580.

As a result of the higher temperature maintained in gas reactor 530,heat flows to pyrolysis chamber 502 through partition 534, both byconvection through the apertures and by conduction through the metallicpartition material, thereby providing at least a portion of the heatrequired to drive the endothermic pyrolysis reaction in chamber 502.

The gas mixtures in both pyrolysis chamber 502 and gas reactor 530, eachof which include inert gas 512 and pyrolysis gas, flow through theapertures of cylindrical partition 572 into combustion reactor 580. Thepyrolysis gas in these mixtures, and the carbonaceous product dischargedvia inlet 545, combust in combustion reactor 580 in the presence of air540, producing an elevated temperature suitably higher in the combustionreaction zone than the adjacent pyrolysis and carbon deposition reactionzones. Heat thus flows from combustion reactor 580 to both pyrolysischamber 502 and gas reactor 530 through partition 572, by convectionthrough the apertures and by conduction through the metallic partitionmaterial, to provide at least a portion of the heat of reaction for theendothermic pyrolysis and carbon deposition reactions.

Pressure differentials are maintained between combustion reactor 580 andeach of pyrolysis chamber 502 and gas reactor 530 as a result of thedesign of apertures in partition 572. These pressure differentials, andthe resulting flow velocities of gas mixture through the apertures, aresufficient to prevent or suitably limit ingress of oxygen fromcombustion reactor 580 into pyrolysis chamber 502 and gas reactor 530.

Heat transfer through partitions 534 and 572 is highly efficient, as aresult of the combined convective and conductive heat transfer modes.The heat of combustion produced in combustion reactor 580 is sufficientto provide both the heat of carbon deposition in gas reactor 530 and theheat of pyrolysis in pyrolysis chamber 502, such that an external energyinput into the process is not required. Optionally, excess heat ofcombustion may be used to generate steam (not shown).

The carbon deposition products, such as carbon fibers, carbon nanofibersand the like, are expected to be of superior quality compared to thosefrom at least some prior art pyrolysis processes, for example on one ormore metrics such as increased surface area, porosity and improvedmorphology, due to improved heat transfer in the pyrolysis reactionsystem 500.

A related embodiment of the invention is depicted in FIG. 14, whichschematically depicts pyrolysis reaction system 600. Similarly numbereditems are as described for pyrolysis reaction system 500 with referenceto FIG. 13, and system 600 operates according to similar principles assystem 500 except as described hereafter. In system 600, cylindricalpartition 572 is an impermeable metallic wall, through which the gasmixtures in pyrolysis chamber 502 and gas reactor 530 cannot flow.Therefore, gas reactor 530 includes off-gas duct 584 through whichoff-gas 585 is removed and sent to combustion reactor 580 via gas inlet561. The unreacted pyrolysis gas in this feed combusts in combustionreactor 580, together with solid pyrolysis product discharged via solidfuel inlet 545. In this embodiment, the heat of combustion flows byconduction from combustion reactor 580 to both pyrolysis chamber 502 andcarbon deposition reactor 480 through impermeable partition 572, therebydriving the endothermic pyrolysis and carbon deposition reactions.

A further variation, applicable to both systems 500 and 600, is that atleast one monolith, which includes a catalyst, is located in gas reactor530 to provide a support for the growth of carbonaceous depositionproducts such as carbon fiber or carbon nanomaterials. In this case, theparticulate fluidisable catalyst is not fed to gas reactor 530.

Another embodiment of the invention will be described with reference toFIG. 15, which schematically depicts pyrolysis reaction system 700.System 700 comprises cylindrical pyrolysis chamber 602 equipped withfeed inlet 604 through which a pyrolysable organic feed is fed tofluidisation zone 602 a at the bottom of the chamber. The feed may besupplied to inlet 604 by any means, for example using screw feeder 606from hopper 608 as depicted.

Pyrolysis chamber 602 includes gas inlet 610, through which an inert gas612 is fed. Inert gas 612 preferably includes only combustion flue gascomponent 614 during steady state operation, but may be supplemented bynon-reactive gas 616 (such as N₂ or CO₂), for example during start-up.Fan 617 is provided to pressurise inert gas feed 612 via fluidisationgas distributors into chamber 602, thus fluidising the organic feed andsolid pyrolysis products thereof in fluidisation zone 602 a. Pyrolysischamber 602 includes product outlet 618 for discharging solidcarbonaceous pyrolysis product 620, in the form of biochar, from thefluidised bed.

Pyrolysis reaction system 700 further comprises gas reactor 630surrounding pyrolysis chamber 602. The interior of gas reactor 630 is anannulus between impermeable cylindrical outer reactor walls 632 andcylindrical partition 634, which defines a boundary between chamber 602and reactor 630. The cross-sectional configuration of pyrolysis chamber602 and gas reactor 630 is schematically depicted in plan view in FIG.15A.

Gas reactor 630 is a primary combustion reactor for combusting pyrolysisgas produced in pyrolysis chamber 602, and thus includes port 638 forintroducing primary air 640 and duct 642 for withdrawing combustion fluegas 644. Port 638 and duct 642 are at the top and bottom of gas reactor630 respectively. As seen in FIG. 15A, port 638 is configured to feedair 640 tangentially into annular gas reactor 630. Thus, in use, acyclonic or vortex-like flow is created adjacent outer reactor walls632, as depicted by arrow 609. The combustion zone in reactor 630 maythus advantageously be located close to outer walls 632, and thusremoved from partition 634. To this end, the internal surface of reactorwalls 632 may also be configured to induce ignition, for example withconventional refractory linings having thermal inertia suitable forflameless combustion.

Cylindrical partition 634 includes impermeable lower portion 634 a andmesh upper portion 634 b. Lower portion 634 a, which lacks apertures butis provided with fins 611 for improved conductive heat transfer, is ofsufficient height to retain fluidised solids in fluidisation zone 602 a.Upper portion 634 b includes a plurality of apertures in the mesh whichprovide fluid communication between pyrolysis chamber 602 and gasreactor 630. Partition 634 is configured such that, in use, gases willflow through the apertures from a higher pressure in pyrolysis chamber602 to a lower pressure in gas reactor 630, but heat will flow in theopposite direction. Moreover, it is believed that the vortex flow in gasreactor 630 will lower the pressure adjacent the partition, thus drawinggas through the mesh apertures from the pyrolysis chamber and limitingthe reverse flow of oxygen.

As will be further described below, combustion in gas reactor 630 isgenerally intentionally incomplete and flue gas 644 thus includesunreacted pyrolysis gas. This flue gas is fed into secondary combustionreactor 681 via port 661, and the residual pyrolysis gas is combusted inthe presence of secondary air 659, fed via port 675. Hot secondary fluegas 673 leaving reactor 681 via duct 663 is at least partially recycledto form combustion flue gas component 614, with a portion sent toexhaust system 662 as needed. Optionally, excess heat of combustion insecondary combustion reactor 681 may be used to generate steam (notshown) or otherwise recovered for purposes of energy efficiency.

In use, a pyrolysable organic feed is fed via feed inlet 604 to thefluidisation zone of pyrolysis chamber 602, and fluidised with inert gas612. At the target temperature (such as between 400° C. to 750° C.)maintained in chamber 602, the feed pyrolyses to produce hot pyrolysisgas and solid carbonaceous pyrolysis products. After a suitableresidence time in chamber 602, carbonaceous pyrolysis product 620 isdischarged via product outlet 618. The pyrolysis gas product combineswith inert gas 612 to form a combustible gas mixture.

This gas mixture flows through the apertures in partition 634 and ispartially combusted in gas reactor 630 in the presence of air 640. Heatof reaction flows through partition 634 into chamber 602, both byconvection through the apertures in upper portion 634 b and byconduction through the metallic partition material of both upper andlower portions. The flow rate of air 640 into gas reactor 630 iscontrolled to provide only the heat needed to drive the exothermicpyrolysis reactions in pyrolysis chamber 630. For example, the flow ratemay be regulated responsively to a temperature measured within thefluidised bed, so as to target a constant pyrolysis temperature. Thetemperature in primary combustion reactor 630 will typically be between50° C. and 200° C. higher than in pyrolysis chamber 602.

Flue gas 644, containing residual pyrolysis gas, is then combusted insecondary gas reactor 681. The flow rate of secondary air 659 to thiscombustion is controlled to ensure that secondary flue gas 673 has a lowoxygen content, for example less than 4 mass % O₂, and preferably lessthan 1 mass % O₂. Advantageously, the hot secondary flue gas may then berecycled and used as inert gas 612, thus avoiding (or minimising) theneed for an external source of inert gas such as utility N₂.Furthermore, the high temperature of the recycled combustion flue gascontributes to driving the endothermic pyrolysis reaction in chamber630.

Pyrolysis of Biosolids

Embodiments of the pyrolysis reaction system disclosed herein may beuseful in pyrolysis of biosolids. Depicted in FIG. 16 is a block flowdiagram of a process for converting biosolids, a by-product of awastewater treatment plant, into biochar.

Wet biosolids 1000, containing c.a. 40 wt % solids, is dried in rotarydrier 1002, which is heated with burner 1004 fed by natural gas 1006 andair 1008. Dried biosolids 1010, now with a solids content of c.a. 80 wt%, is fed to pin-mill grinder 1012 to reduce the biosolids to a particlesize appropriate for fluidisation. Rejected fines 1014 are removed fromthe process, and the particulate biosolids are classified in sieveshaker 1016 and fed as biosolids feedstock 1020 to pyrolysis reactionsystem 800 according to the present invention. Pyrolysis reaction system800 thus includes pyrolysis chamber 802 and combustion chamber 830,separated by partition 834 having a plurality of apertures. Optionally,pyrolysis system 800 may be according to embodiments disclosed herein,for example pyrolysis reactions systems 30, 100, 180 or 700 describedwith reference to FIGS. 2, 8, 9 and 15 respectively.

Biosolids feedstock 1020 is pyrolysed in chamber 802 in the presence ofinert gas 812, which consists of recycled combustion flue gas 814 duringsteady-state operation. Biochar product 820 is discharged from thepyrolysis chamber. The mixture of gas 812 and the produced pyrolysis gasflows through partition 834 into combustion reactor 830, where thepyrolysis gas is combusted in the presence of air 840. Air 840 ispreheated by heat exchanger 856 (using the heat in combustion flue gas814) and/or by pre-combustion in burner 1022 with natural gas 1024 (forexample during start-up). The heat of combustion in reactor 830 flowsefficiently into chamber 802, thus driving the pyrolysis reaction asdescribed herein. Hot flue gas 814, with low O₂ content due tocombustion, passes through heat exchanger 856 and a portion is recycledto form inert gas 812. A second portion is sent to wet/dry scrubber 1026and bag filter/activated carbon bed 1028 for purification, and thenvented via exhaust 1030.

The biochar produced in this process may advantageously be free ofpathogens and microplastics present in the biosolids, and certain othercontaminants, such as heavy metals and per- and polyfluoroalkylsubstances (PFAS), may be destroyed, removed or immobilised in thebiochar. The biochar may have excellent properties, for example one ormore of favourably slow release of phosphorous when added to soils, highsurface area, cation exchange capacity, oxygen containing functionalgroups and desirable pH due to the temperature control during pyrolysis.

EXAMPLES

The present invention is described with reference to the followingexamples. It is to be understood that the examples are illustrative ofand not limiting to the invention described herein.

Example 1

The pyrolysis of biosolids (40 g), fluidised in N₂ (1 litre/min), wasinvestigated at a range of temperatures. The morphology of the biocharwas found to be strongly dependent on the temperature of pyrolysis.FIGS. 17, 18, 19, 20 and 21 depict scanning electron microscopy (SEM)images of biochar particles after isothermal pyrolysis at 500° C., 600°C., 700° C., 800° C. and 900° C. respectively. At 500° C., a lowporosity biochar is produced. The porosity increases to a maximum at700° C. At higher temperatures, the porosity drops again as a result ofsintering.

The results demonstrate the importance of excellent heat transfer, andthus temperature control, in pyrolysis reactions. Poor heat transferwill result in uneven temperature distributions, potentially includingreactions zones of sub-optimally low or high temperatures. As a result,both the reaction rate and quality of the biochar may be negativelyaffected.

Example 2

A pyrolysis-combustion demonstration system, as schematically depictedin FIG. 22, was designed and modelled using computational fluid dynamicssimulations. The system included cylindrical pyrolysis chamber 702 andannular combustion reactor 730, separated by a cylindrical partitionwhich included lower impermeable portion 734 a and upper mesh portion734 b. The mesh portion was formed with metallic mesh having 90% openingby area. Feed inlet pipe 704 was provided to introduce pyrolysablefeedstock to fluidisation zone 702 a at the bottom of the pyrolysischamber, and gas inlet 710 to provide pre-heated inert gas (N₂), ofcontrollable temperature, to fluidise the solids in fluidization zone702 a. Outlet 710 was provided to remove solid pyrolysis product. In thecombustion reactor, air inlet 738 provided injection of pre-heated air,of controllable temperature, tangentially to the top of the combustionreactor, with combustion flue gas withdrawn from duct 742 at the bottomof the reactor.

The flow of air, inert gas, and the mixing thereof duringpyrolysis/combustion was modelled, with the results depicted in FIGS.23A-22A using representative flow pathlines. In the simulation, inertgas (500° C.) was introduced at 110 litre/min, air (500° C.) wasintroduced at 40 litre/min, and biosolid was introduced at 0.25 kg/hour.As seen in in FIG. 23A, air injected tangentially into combustionreactor 730 through port 738 resulted in a cyclonic flow near the top ofthe reactor, with subsequent downward flow of air concentrated along theouter walls of the annular combustion reactor. As seen in FIG. 23C,inert gas introduced via inlet 710 flowed out of the pyrolysis chamberthrough the apertures in the mesh partition (only pathlines throughupper apertures shown), and out of the combustion reactor via duct 742.The pressure in the pyrolysis chamber was sufficiently high that theinert gas, carrying combustible pyrolysis gas with it, and the air mixedonly in the combustion reactor, as seen in FIG. 23B. Most of the mixingoccurred near the outer walls of the combustion reactor. Thus, therelittle or no ingress of air into the pyrolysis chamber is expected.

Example 3

A pilot-scale demonstration unit was constructed according to the designdepicted in FIG. 22 and described in Example 2. The temperatures of theinert gas (T_(g)), feed air (T_(a)), pyrolysis reaction zone (T_(p)) andcombustion reaction zone (T_(a)) were measured with thermocouples at thelocations indicated in FIG. 22. The O₂ content (% O₂) in the pyrolysischamber was measured with an online oxygen analyser at the indicatedlocation.

A demonstration run was conducted using biosolids, obtained fromSouth-East Water's Mount Martha plant and dried to a solids content ofapproximately 80 wt %, as pyrolysable feedstock. The particle size wasc.a. 0.05 to 0.4 mm. The inert gas (N₂/CO₂ mixture) and air feeds werepre-heated using an LPG burner. Batches of biosolids feed (500 g and 200g respectively) were introduced at 1.37 and 1.72 hours on line. Nobiochar product was withdrawn during the run. The results are shown inFIG. 24.

Initially, the temperatures of the pyrolysis chamber and combustionreactor were increased by raising the temperatures of the inert gas andair feeds respectively. The O₂ content in the pyrolysis chamber rapidlydecreased to below 1 wt %, indicating that a satisfactory reducingenvironment for pyrolysis reactions was obtained in the pyrolysischamber despite the mesh partition. When the temperature inside thepyrolysis chamber reached a desired operating temperature, the inert gasflow rate was set to the minimum flow rate needed for fluidisation, andthe air flow rate was set according to energy balance calculations. Thepressure of the inert feed gas, before the fluidisation distributorplate, was 1.5 kPa. The pressure measured in the pyrolysis chamber,directly above the fluidisation zone, was 1.2 kPa, and the measuredpressure in the combustion reactor, close to the mesh partition, was 1.1kPa.

A first batch of biosolids was introduced and fluidised in the inert gasflow. The temperature in the combustion reactor (T_(c)) then continuedincreasing even as the air feed temperature (T_(a)) was decreased, andT_(c) exceeded T_(a) for the remainder of the run. This indicates thatexothermic reaction, i.e. combustion of pyrolysis gases originating fromthe pyrolysis chamber, was taking place inside the combustion reactor.The temperature in the pyrolysis chamber (T_(p)) also continued rising,despite the endothermic pyrolysis reaction and maintenance of a constantinert gas feed temperature (T_(g)). This indicates that heat ofcombustion was efficiently conveyed into the pyrolysis chamber to drivethe endothermic pyrolysis reaction therein. The O₂ content in thepyrolysis chamber remained low (below 1.2 wt %) during the pyrolysisreaction (after 2.09 hours on line the O₂ analyser was used to measurethe O₂ content in the combustion flue gas). A second batch of biosolidswas added when the temperature inside the pyrolysis chamber reached 500°C., and this temperature was maintained at steady state for theremainder of the run by regulating the air flowrate.

A number of similar reactions were conducted with different pyrolysistarget temperatures. Biochar yields were generally in the range of 30 to40%. The measured surface area of the biochar was found to be 41, 53 and66 m²/g at pyrolysis temperatures of 500° C., 550° C. and 600° C.respectively.

Those skilled in the art will appreciate that the invention describedherein is susceptible to variations and modifications other than thosespecifically described. It is understood that the invention includes allsuch variations and modifications which fall within the spirit and scopeof the present invention.

Future patent applications may be filed in Australia or overseas on thebasis of or claiming priority from the present application. It is to beunderstood that the following provisional claims are provided by way ofexample only, and are not intended to limit the scope of what may beclaimed in any such future application. Features may be added to oromitted from the provisional claims at a later date so as to furtherdefine or re-define the invention or inventions.

1. A pyrolysis reaction system, the system comprising: a pyrolysischamber comprising a feed inlet, a gas inlet and a product outlet,wherein the pyrolysis chamber is configured i) to receive a pyrolysableorganic feed and an inert gas via the feed inlet and gas inletrespectively, ii) to pyrolyse the organic feed at a pyrolysistemperature to produce a carbonaceous pyrolysis product and a pyrolysisgas, wherein the pyrolysis gas will combine with the inert gas to form agas mixture having a pyrolysis chamber pressure in the pyrolysischamber, and iii) to discharge the carbonaceous pyrolysis product viathe product outlet; a gas reactor configured to react the pyrolysis gasby combustion and/or carbon deposition at a gas reaction temperature anda gas reactor pressure; and a first partition defining a boundarybetween the pyrolysis chamber and the gas reactor, the first partitioncomprising a plurality of first apertures to provide fluid communicationbetween the pyrolysis chamber and the gas reactor, wherein the pyrolysisreaction system is operable with the gas reactor pressure less than thepyrolysis chamber pressure such that the gas mixture flows from thepyrolysis chamber to the gas reactor through the first apertures,thereby providing at least a portion of the pyrolysis gas for reactionin the gas reactor.
 2. (canceled)
 3. The pyrolysis reaction systemaccording to claim 1, wherein the partition is configured such that inoperation the gas mixture flows through the first apertures at a flowrate sufficient to substantially preclude ingress of gas from the gasreactor into the pyrolysis chamber.
 4. (canceled)
 5. The pyrolysisreaction system according to claim 1, wherein the first partitioncomprises a mesh or perforated screen.
 6. The pyrolysis reaction systemaccording to claim 1, wherein the partition is configured such that heatconvects from the gas reactor to the pyrolysis chamber through the firstapertures when the gas reaction temperature is greater than thepyrolysis temperature in operation, thereby providing at least a portionof the heat of pyrolysis in the pyrolysis chamber.
 7. The pyrolysisreaction system according to claim 6, wherein the first partitioncomprises a thermally conductive material such that heat conducts fromthe gas reactor to the pyrolysis chamber through the thermallyconductive material when the gas reaction temperature is greater thanthe pyrolysis temperature in operation, thereby providing anotherportion of the heat of pyrolysis in the pyrolysis chamber.
 8. Thepyrolysis reaction system according to claim 1, wherein: i) thepartition comprises a plurality of protruding members, such as tubes orfins, that extend into the gas reactor and/or the pyrolysis chamber,wherein at least a fraction of the first apertures are located on theprotruding members; and/or ii) the partition comprises a plurality ofspaced apart sheet members, such as plates or meshes, that extend atleast partially in a transverse orientation between the gas reactor andthe pyrolysis chamber, wherein at least a fraction of the firstapertures are located between the spaced apart sheet members.
 9. Thepyrolysis reaction system according to claim 1, wherein the gas reactorcomprises a port for introducing a gas containing oxygen and a duct forremoving flue gas, wherein the gas reactor is configured such that inoperation the pyrolysis gas will react by combustion with the oxygen.10. The pyrolysis reaction system according to claim 9, wherein the gasreactor comprises an annulus surrounding the pyrolysis chamber and theport is configured to introduce the gas containing oxygen tangentiallyinto the gas reactor such that a vortex flow around the pyrolysischamber is produced in at least a part of the annulus.
 11. (canceled)12. (canceled)
 13. (canceled)
 14. The pyrolysis reaction systemaccording to claim 1, wherein the gas reactor is configured such that inoperation the pyrolysis gas will react by carbon deposition on acatalyst in the gas reactor, thereby forming a carbonaceous depositionproduct, wherein the gas reactor further comprises a catalyst feed inletfor feeding a particulate catalyst and a product discharge port fordischarging a carbonaceous deposition product.
 15. (canceled)
 16. Thepyrolysis reaction system according to claim 14, further comprising: acombustion reactor comprising a port for introducing a gas containingoxygen and a duct for removing flue gas, wherein the combustion reactoris configured to combust a fuel with the oxygen at a combustiontemperature; and a second partition defining a boundary between thecombustion reactor and at least the gas reactor, wherein the secondpartition is configured such that heat of combustion transfers from thecombustion reactor to the gas reactor through the second partition whenthe combustion temperature is greater than the gas reaction temperaturein operation, thereby providing at least a portion of the heat of carbondeposition in the gas reactor.
 17. The pyrolysis reaction systemaccording to claim 16, wherein the second partition comprises aplurality of second apertures to provide fluid communication between thecombustion reactor and the gas reactor, wherein in operation: i) aportion of the pyrolysis gas flows from the gas reactor to thecombustion reactor through the second apertures, wherein the fuelcombusted in the combustion chamber comprises the portion of thepyrolysis gas; and ii) the heat of combustion transferred through thesecond partition at least partially convects through the secondapertures.
 18. (canceled)
 19. The pyrolysis reaction system according toclaim 16, wherein the pyrolysis chamber is configured to discharge thecarbonaceous pyrolysis product into the combustion reactor, wherein thefuel combusted in the combustion chamber in operation comprises thecarbonaceous pyrolysis product.
 20. (canceled)
 21. (canceled) 22.(canceled)
 23. (canceled)
 24. The pyrolysis reaction system according toclaim 1, wherein the pyrolysis chamber is configured to fluidise solidscomprising the organic feed and/or the carbonaceous pyrolysis productwith the inert gas.
 25. The pyrolysis reaction system according to claim1, wherein a flue gas produced by combustion of the pyrolysis gas in thepyrolysis reaction system is directed to form at least a portion of theinert gas.
 26. A method of pyrolysing an organic feed, the methodcomprising: feeding a pyrolysable organic feed and an inert gas to apyrolysis chamber; pyrolysing the organic feed at a pyrolysistemperature to produce a carbonaceous pyrolysis product and a pyrolysisgas, wherein the pyrolysis gas combines with the inert gas in thepyrolysis chamber to form a gas mixture having a pyrolysis chamberpressure; discharging the carbonaceous pyrolysis product from thepyrolysis chamber; flowing the gas mixture to a gas reactor through aplurality of first apertures in a first partition, wherein the firstpartition defines a boundary between the pyrolysis chamber and the gasreactor; and reacting the pyrolysis gas in the gas reactor by combustionand/or carbon deposition at a gas reaction temperature and a gas reactorpressure, wherein the gas reactor pressure is less than the pyrolysischamber pressure.
 27. (canceled)
 28. (canceled)
 29. (canceled)
 30. Themethod according to any one of claims 26 to 29, wherein the gas reactiontemperature is greater than the pyrolysis temperature, wherein heatconvects from the gas reactor to the pyrolysis chamber through the firstapertures, thereby providing at least a portion of the heat of pyrolysisin the pyrolysis chamber.
 31. (canceled)
 32. The method according toclaim 26, further comprising introducing a gas containing oxygen intothe gas reactor and reacting the pyrolysis gas by combustion with theoxygen.
 33. (canceled)
 34. (canceled)
 35. The method according to claim26, further comprising reacting the pyrolysis gas by carbon depositionon a catalyst in the gas reactor, thereby forming a carbonaceousdeposition product.
 36. (canceled)
 37. (canceled)
 38. The methodaccording to claim 35, further comprising combusting a fuel with oxygenin a combustion reactor at a combustion temperature greater than the gasreaction temperature, wherein heat of combustion transfers from thecombustion reactor to the gas reactor through a second partition thatdefines a boundary between the combustion reactor and at least the gasreactor, thereby providing at least a portion of the heat of carbondeposition in the gas reactor; and wherein the second partitioncomprises a plurality of second apertures providing fluid communicationbetween the combustion reactor and the gas reactor, wherein: i) aportion of the pyrolysis gas flows from the gas reactor to thecombustion reactor through the second apertures, wherein the fuelcombusted in the combustion chamber comprises the portion of thepyrolysis gas; and ii) the heat of combustion transferred through thesecond partition at least partially convects through the secondapertures.
 39. (canceled)
 40. (canceled)
 41. The method according toclaim 38, wherein the carbonaceous pyrolysis product is discharged intothe combustion reactor, wherein the fuel combusted in the combustionchamber comprises the carbonaceous pyrolysis product.
 42. (canceled) 43.(canceled)
 44. (canceled)